Time to throw my hat into the mix.
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Design: Oh, boy. It's a seal. Actually, no, I'll give it credit where it's due. It's a
bigger seal.It doesn't even look like it's
unoriginal namesake. At least do another crappy pun on the word seal like your pre-evo did. I feel like I could go to a zoo and see this thing. There's nothing that stands out.
Concept: Was there one? Honestly, what basis is there other than 'Oh, look, an animal that lives in the ocean, we need a couple of Ice types, let's put this guy in for Dex fodder!'. It comes along with every other water type in Gen 1 (Cinnabar Island/Seafoam Islands), and there's no reason to use over Cloyster (better defence), Lapras (better stats), Jynx (Psychic type) or Articuno (obvious reason - hell, it's in the same place, so why not catch Articuno instead?). No concept, no purpose, get out of here.
Competitive/In Game: First off, competitive. This thing has terrible stats (475 BST, best stat is 95 spdf), base 70 offensive stats means no use at all as an attacker. It's type grants no favours and it's abilities are useless. It's move pool is barren, being one of those cursed Water types to not get Scald, and one of the cursed Ice types to not get Freeze Dry. No reliable recovery, having no offensive presence and little defensive impact make this thing terrible.
Next, in game. This thing is the worst thing to run into in-game (now especially in Sun & Moon), but it has a bane on anybody doing a Nuzlocke. Why? Well, let's exclude the common moves of Whirlpool/Toxic or Perish Song (one of the most common and only viable movesets this thing can have. This little sh*t learns Sheer Cold. Not only that, it learns it not only by evolution in SuMo, but also earlier than all other Pokemon at level 34 in all other games (don't count Suicune, he has to relearn that). The number of Pokemon I have lost to that thing is immeasurable. Honorable mentions include Mewtwo, Delta Snorlax (Pokemon Insurgence), Alolan Raichu - the list goes on (For context, those have been randomiser nuzlockes). This Poke-burden should be expelled from the Pokedex immediately.
Rant over. I honestly hate this thing with a burning passion. I hope you feel the same.