Mega Venusaur has a nice design, even if it wasn't changed that much from standard Venusaur's design. It's a good wall, but it doesn't have many options to use outside of the typical Leech Seed and Giga Drain. It's lucky to have Sleep Powder though, and Thick Fat was a brilliant idea.
Mega Charizard X is a very cool redesign of Charizard. The black complimented with the blue flames is pretty interesting. It turns into the opposite of standard Charizard as a Physical attacker, and a very powerful one too.
Mega Charizard Y has the great niche of Drought to increase its fire-power, and instant access for Solar Beam. Its design isn't too changed from standard Zard, and I'm not a huge fan of it, but it's acceptable.
Mega Blastoise is good for multipurpose. It has nice access to Rapid Spin, but my problem is that Mega Launcher makes it one sided. You have a pretty good idea of what it will run, and this why Mega Launcher isn't a favorite ability of mine. Still, I like using it, even if it is a bit generic as a bulky offensive water type. The design is a bit funky, and even in an interview, a Game Freak worker said that they all felt that Blastoise's design was a bit funky looking. You could probably find it buried in the website's archive.
Mega Beedrill has a kickass Beedrill design and is a huge glass cannon. It's big gamble to use one, and it can't afford to be hit. I have used one before, and it's actually pretty satisfying watching it wallbreak. Definitely the improvement Beedrill needed. Now about Butterfree....
Mega Pidgeot also suffers from being one sided. Focus on Special attack hurt. And it wasn't like Blastoise or Lopunny where they changed the movepool to help it out. Mega Pidgeot is just kinda stuck as a Special Attacker. Heat Wave, Hurricane, U-Turn, Roost. No Guard is awesome, but that means you have to deal with 100% accurate Thunders and Stone Edges. Still pretty enjoyable to use, and a nice design.
Mega Alakazam is also a glass cannon, and a special one. Ridiculous firepower, faster than a Ninjask, it can easily sweep so long as it doesn't miss or get hit by a physical attack. Seriously, a half-decent Crunch will do loads of damage to this thing. While I have yet to use it, I do think it looks fun. The design is decent, but what happened too his legs? Did he get mercury poisoning or something?
Mega Slowbro is one I have yet to use. Looks like a pretty annoying wall. I'd love to try it out sometime. The design looks okay, but I kinda wish they went for something else. First off, I don't like how they changed his jolly facial expression to something so depressing. Kinda like Oshawott's ^ mouth. Seriously, I could kick Slowbro over and it couldn't battle anymore. Also, I like how it reflects the movements of other trainers' Slowbro in the anime, which usually spun on the tip of their shell. Still wish they tried a different design choice.
Mega Gengar can be decent in Ubers, but a bit too frail for my taste. It's powerful, and Shadow Tag makes it great, but it also hurts him because he's kinda overwhelmed in the Ubers tier. Nice design though, I especially like the different shades of purple. That Perish Trapping tho.
Mega Kangaskhan can be a pain to face off against. Sucker Punch, Return, Fake Out, Power-Up Punch, and Parental Bond are pains in the ass. Otherwise, it's a pretty ordinary Mega with underwhelming stat boosts. But that ability changes
everything. Nice concept too- pretty original.
Mega Pinsir surprised me like everybody else with the Flying typing, but they way they introduced it with Aerilate was genius. Even though you need to be weary of the Rocks, you have goddamn Aerilated Quick Attack. Nobody fucks with Aerilated Mega Pinsir. "DON'T FUCK WITH THIS PINSIR!" Very fun to use.
Mega Aerodactyl is useless due to being outclassed by its regular self with the Life Orb. It's still decent, but not my first choice for a Mega slot. Nice rock goatee though.
Mega Mewtwo X is opposite of standard Mewtwo in that he's designed to be a Physical attacker. Too bad he's basically only got Drain Punch for the Fighting type move, unless you choose to go mixed for STAB Focus Blast. Design looks like he has some weird lumpy suit on him.
Mega Mewtwo Y is my favorite of the two. The crotch hat was nice touch, and although its movie appearance was
awful, it pimps out with the highest Special Attack in the game. Respect. Practically god like. Mega Evolution with Mewtwo was not necessary, however, and it makes little sense. Mega Stones were developed by AZ's weapon, before Mewtwo was even created. So it makes no sense for him to even have
one Mega Stone.
Mega Ampharos has no need for the Dragon typing, and all she has to use for it is Dragon Pulse. Technically, you could use Outrage, but a base Attack of 95 in comparson to a Special Attack of 165 says not. Although the Dragon typing was useless, Mega Ampharos was handy in giving Amphy more bulk. Haven't used her, but I'm looking forward trying it out at some point. Decent design- not great, not horrible.
Mega Steelix is what happens when you don't pay attention to how you design a Mega. It's essentially Mega Aggron, but more offensive. Don't get me wrong, I'm sure Mega Steelix is great, and I really would like to use it, but for now, Mega Aggron is a bit better since it has Filter on its side. As an offensive Mega Aggron, it works out well. Plus, it's Steelix. He deserved a Mega. Cool design too.
Mega Scizor has a weird design. What with the peglegs and the crazy kindergarten scissor blades. Regular Scizor has a cooler appearance, but Mega Scizor does great on capitalizing the Swords Dance set, and providing decent bulk as well. Swords Dance is my favorite set for Scizor, so a Mega that capitalizes on it gets my seal of approval. I've used it, and it's honestly not that much different from standard Scizor.
Mega Heracross is awesome! Skill Link is amazing. I've Baton Passed it some Agilities and Swords Dances. It wrecks shit up. Spamming these multi-hit moves is so fun. I never want to use standard Heracross again! Nice design too. Arm Thrust is underrated. At least
Arm Thrust doesn't lower your Defenses.
http://replay.pokemonshowdown.com/almostanyability-213347980 Even in AAA, this thing comes out with sparkling colors.
Mega Houndoom is forgettable. Solar Power requires too much support for me to like it, and if you don't use it- congrats, you have a useless ability. I understand it makes you more powerful, and BL2 (or wherever it is) is a good ranking for it. I almost never see it. It's just "eh." Thank goodness they improved the Speed though. And hey, I still like it. Cool design too.
Mega Tyranitar is neat. Tyranitar didn't need a Mega, but this was a welcome addition. Although he's kinda forgettable in my opinion, he is a
must for Sand Teams. Can be very powerful, Stealth Rock and Dragon Dance fucks everything up. Regular Tyranitar on steroids. Cool design too, though I don't know how it moves around with those branchy appendages.
Mega Sceptile is awesome. He's amazing casually. My favorite of the Hoenn starter Megas. The Dragon typing was also a bit more justified, and it had
just enough to work with it. I kinda prefer Unburden Sceptile a bit more, but in OR/AS story mode- where I used him the most- he was a blast. I have used him competitively- he's not bad in that department either.
Mega Blaziken is a Mega of my second favorite Pokemon. If you don't have Speed Boost on your regular, don't worry- there's this Blaziken to use. I like regular Blaze's design more, but this one isn't bad. Speed Boost spam and slightly more bulk help Blaziken butt rape the opposition. Not too much different from regular Blaziken.
Mega Swampert is a hard design to get used to, the best comparison I can think of being Emboar. But when you get around the girth of it, and you realize that Mega Swampert is actually buff- not fat- you start to appreciate it. A powerhouse, can work for bulky offense, has Stealth Rock access, can spam Swift Swim- perfect Mega.
Mega Gardevoir invented Pixelated Hyper Voice, and although outshined by Mega Altaria, I still like her. I like her habit of always standing under a running air vent, and is a pleasing upgrade for any Gardevoir fan. Recently, I've grown to like Gardevoir, and I'd like to try her Mega Evolution out sometime. Iron Head sucks though.
Mega Sableye is just surprising. His regular form's version of Prankster gets really annoying, and its access to Recover doesn't make things easier for you. Magic Bounce means you can't cripple it, so you can't interrupt its walling fun. It can plague your team with Will-O-Wisp and I have to say that I love the Ruby / Emerald. Cool design, amazing at being a wall- perfect Mega.
Mega Mawile is unfortunately cursed with a banishment to Ubers. It's outclassed there and at the bottom of viability rankings. But at least
I like her. She's a blast to use in Ubers, Sucker Punching Deoxys and all of that stuff. Base 210 Attack could be imagined as unimaginable before Gen six. Way to go Mega Mawile! Cool design too. Named my Mega Mawile "Horn Problem."
Mega Aggron was nice to use. Even though he didn't match my playstyle, he's a good Stealth Rock user. Filter makes it difficult to take him down, and what makes it harder is the loss of the Rock typing. The Sp. Defense is kind of a downer, and the biggest reason why I didn't like using Mega Aggron. Water wrecks you, as do Strong Fire type moves. Cool design though, I really like the emphasis of making Aggron look like a wall.
Mega Medicham is forgettable too. I've only used it once in a ranbat. I think Pure Power buffs its Attack to like... 200. Still not the same as Mega Mawile though, especially since outside of Attack, it's just your regular, mundane Pokemon. The typing might also be a factor. Lack of priority hurts it too. Design is pretty generic too, but I like it nonetheless.
Mega Manectric is just a Manectric with more power. Intimidate is nice to help screw around with your opponents, and it can take advantage of this thanks to STAB Volt Switch and Electric only having one huge weakness. Some think the design is kinda silly looking, but I think it fits Manectric well. Glad to see that they acknowledged its popularity.
Mega Sharpedo is weird, since it requires you to set up with Speed Boost first, and then go into the more powerful Mega Sharpedo. Strong Jaw is about as useless as Mega Launcher, only giving you the options of Crunch and Ice Fang. Otherwise, you have to waste a slot on Protect, and you're pretty predictable. Not to mention frail as well. Reliance on Speed Boost is a bit harsh. When it sets up, MegSha is a powerhouse, but if you get taken out too early, you just wasted your Mega slot. And when they were Mega Evolving this thing, I was kinda expecting them to give it a butt, but instead, they extended the other end of his body instead. And hey, I still like Mega Sharpedo. He's fun to use, especially in Monotype.
Mega Camerupt is a well-designed Mega. They made him a volcano camel. It's beautiful. Not even joking. As far as how it plays, it's pretty powerful offensively, and is guaranteed to fuck your shit in Trick Room. I used it back when it was NU, and it was pretty enjoyable. In the sun, you'd better hope you can take it out quickly. The slow speed is a bit of a downer, but to be fair, I don't know how you could make something like Camerupt a speed racer.
Mega Altaria schooled Sylveon and Mega Gardevoir. She's bulky and incredibly difficult to eliminate, no thanks to Roost, and with Pixilated Hyper Voice, as well as a very good defensive typing- Mega Altaria is a monster. It's powerful, yet tricky to take it out. The design is kinda lacking- just a bunch of clouds. But imagine taking a nap in that fluff.
Mega Banette's game revolves around Prankster. Prankster Will-O-Wisp, Prankster Destiny Bond- both are huge things to be careful of when facing it. After being in Dusknoir's shadow for so long, it was nice to see it score a Mega while he watched Dusknoir rot away in PU (I still like Noir tho). A large Attack stat makes STAB Shadow Sneak pretty strong, and it gets stuff like Sucker Punch. It would have been nice if they could have added the Dark typing, but what are you gonna do? Cool design as well.
Mega Absol fixed everything that made regular Absol lacking. It's designed to be an offensive sweeper, and it has a large movepool to do this. Decent Speed, great Attack, and usable Special Attack work nicely. Too bad it can't take any hits. Beware of Magic Bounce too folks- take it from a guy who always forgets about it. Sucker Punch from Mega Absol will wreck you. Cool design too, really capitalizes on Absol's concept.
Mega Glalie is one of my favorites. It was nice seeing him climb up to RU. Although the nice argument was presented that wasting your Mega Slot on something you're going to just Trash in the end is a bit pointless, I still like Mega Glalie. I have yet to release the Refrigerated Tsar Bomba, but I've got a Glalie named Mo that I use casually in OR/AS. Refrigerated Headbutt does the job nicely, and you don't have to recharge or waste a Revive. Cool design too, but I kinda feel bad that he had to break his jaw to achieve that. 100 Speed isn't enough to work with, but still, I'd gladly take one into battle. As always- set up your hazards and explode yourself.
Mega Salamence is the perfect way to Mega Evolve Salamence. You give it the essential Flying type powerhouse ability, Aerilate, ridiculous stat upgrades, a hang glider for wings, and he's all set. I haven't used one, but I bet it's awesome.
Mega Metagross is so much fun. They tried to ban him from OU, but you can't tell this guy where to go. He eats up hits perfectly and destroys everything with its Attacks. Nice design too. Great Mega Evolution to a Pokemon who was previously the one most robbed of a Mega.
Mega Latios seems to be more popular than
Mega Latias, but I like Latias better overall. Probably because of the Defenses. Basically what you'd expect from OU Dragons. Not much to say here.
Primal Groudon is amazing to use, and a staple to any Ubers team. With my Primal Groudon, Do U Even Sun?!, we get rid of as many threats to the team as we can. Spam Precipice Blades! Show no mercy to those Water type bastards! Desolate Land will wreck you! Truly everything the previously outshined Groudon needed.
Primal Kyogre isn't as good as Primal Groudon, since the rain can't be used to support the rest of the team. And being able to blot out a type that youw ere resistant to anyway doesn't help. You're still pretty good though, and you still get to spam Thunder, but I'd rather use Primal Groudon. Scarf Kyogre is the way I'll go with Ubers Water types.
Mega Rayquaza's mighty wins can blow away sunlight, rainfall, sleet, and sandstorms. Delta Stream gets rid of his weaknesses and completely eliminated the glue that held the Pokemon Meta together. They had to create the most fucked up tier for him so that he wouldn't terrorize the Ubers tier.
Awesome design though.
Mega Lopunny is a nice improvement to what was previously a sub-par normal type. Scrappy meant it didn't need to worry about Ghosts, High Jump Kick meant it got an essential STAB, Normal/Fighting proved to pair well, and your sweeping abilities and movepool are amazing. Very much fun to use. Design is decent.
Mega Garchomp isn't as fun as standard Garchomp. You have to lose some Speed, and that changes it all. I'll just stick to eating some Leftovers and spamming Swords Dance behind my Substitutes if that's okay. I still like him though. Not as bad as a design as people say, though I can understand why some may not like it. I myself prefer original Garchomp's design to Mega Garchomp's.
Mega Lucario is awesome! I love Lucario so much. Very fun to use, and a rather cute Pokemon to tickle.... Cute little jellybean piggies.... ... In the show, he can pair well with any trainer, even the annoying ones (some guy named Camera or something). Giving Mega Lucario Adaptability meant that he could wreck Fairies and anything else weak to Steel or Fighting. He gets more priority moves than any other Pokemon I have ever come across. Haven't used one competitively, but casually, he's very fun to use.
Mega Abomasnow is a must for Hail teams, but since Hail isn't that viable, Mega Abomasnow isn't so much so either. Still, in the Hail, it's very powerful, and it's typing- while horrible- is nice offensively and pairs together to make a nice movepool. Ice Shard is always nice, as is the recovery Abomasnow is gifted with by his Grass typing. Fun to use, but the typing is a downer. Cool design.
Mega Gallade has... Inner Focus? Why? Ugh, that aside, pretty much regular Gallade with stat boosts. Nothing new (seriously... you couldn't even have used Steadfast?). But hey, it's still decent. I don't know much about Megallade. Not too much to say. Cool design- nice cape.
Mega Audino is NU's prized Mega Evolution. Kinda similar to Cresselia. Great bulk, nice movepool, several sets, fun to use, cool design. No complaints here.
Mega Diancie is a pain. It can set up Rocks, can be an anti lead (because they
had to give it Magic Bounce), and gave it ridiculous offenses. Diamond Storm's secondary effect is a total bitch to deal with. I haven't used Mega Diancie yet. Looks like something I would enjoy though.
And that's all of my thoughts on the Megas. I sure hope this doesn't violate any rules, because I worked all night on this post....