Prefacing by saying I'm not exactly an active player of Gen 4, but neither are several other posters here and I like policy discussion + spectate a decent amount of both so I'll give my two cents.
Hot take: looking at the arguments here, it really seems like
the issue is quite particularly with Jirachi, and more specifically Serene Grace, bringing the level of RNG too high compared to other luck-based elements. Don't worry, I am not about to suggest destabilising a meta I don't play by removing its best Pokemon, I am not that dumb!! But if modding is on the table, there's another solution that solves multiple problems at once instead of being what seems to be a subtle, fairly ineffective attempt to nerf a controversial Pokemon. Please only post your laugh reacts once you're done reading.
I'd like to propose
modding Serene Grace to have no effect in these Generations. You can call it Serene Grace Clause if you want.
To address questions you probably have:
Why?
The Ability pretty much only causes headaches, both in terms of tiering policy and its in-battle effects. Poor Jirachi in DPP has been suffering from success for a long time because of it; the Pokemon is fundamentally amazing, but add literally twice as much variance to it as anything else in the metagame and of course it'll feel awful to fight. The tier needs Jirachi, but Serene Grace makes that a rough deal because there's really good odds something stupid will happen. At least, this is what I have seen from
multiple posts over my time on this site, and
the results of the recent DPP tiering survey showing that 100% of people think Jirachi is unhealthy but only 20% think it can be removed from the tier. People think Jirachi is problematic, but they don't have a solution due to its unique circumstance in having Serene Grace as its only Ability, and banning it being suboptimal because every other aspect of the Pokemon is healthy for the metagame. No banning Sand Veil to save BW Garchomp here, that would be far too impactful on such an established Generation. Ice Punch freezes are just another part of the annoyance that is Jirachi- Body Slam + Iron Head ParaFlinches, timely Fire Punch burns, etc.. Any Pokemon can make these things happen, it's just that it's far more likely with Jirachi (and, uh, Dunsparce). Serene Grace having a healthy impact on the game is practically nonexistent- it makes Togekiss stand out, and whether it does that in a healthy manner is up to your judgement, but that's about it really. Serene Grace Clause has minor collateral and solves both the primary issue with Freeze
and the issue that stops Jirachi being a healthy part of the metagame by bringing its variance in line with other Pokemon.
Slippery slope! Let's mod Drizzle to do nothing and unban Kyogre.
Luckily, this isn't the case- the impact of these Abilities are totally different. I'll split abilities into two categories to explain this, those being
Raisers and
Enhancers.
Raisers are Abilities like Drought, Clear Body, Unseen Fist, Intimidate, Tough Claws, Magic Guard, Intrepid Sword, Water Absorb, Flame Body, and so on- they raise the Pokemon's peak potential and let them do something they couldn't do before, whether that's more maximum damage, better peak defensive capabilities, the potential to bypass checks or ignore setup, whatever it may be.
Enhancers, on the other hand, don't impact your Pokemon's peak potential- instead, they simply make your Pokemon
more likely to reach that potential. This is stuff like Super Luck, Wonder Skin, Compound Eyes, and, of course, Serene Grace. These Abilities have absolutely no impact on what a Pokemon could potentially achieve, but they make achieving that potential occur on a higher basis. I think equating such Abilities is a fundamental mistake, as removing the latter has little to no impact on what good players should account for when fighting the Pokemon (yes, you might get crit or flinched when fighting an Absol or Jirachi anyway, even if it's less likely), while removing the former objectively decreases the threat level of the Pokemon (Kyogre now has more safe switchins as it does less damage). Of course, modding out an Ability to remove it shouldn't be a primary solution for problematic Enhancers, but when one is uncompetitive and near-impossible to take tiering action on otherwise, I think it's seriously worth considering. When all is said and done, Jirachi can still do everything it could without Serene Grace Clause, but it's put in line with its competition in terms of variance and therefore uncompetitiveness.
EDIT: Also I trust people to not be idiots, this is a very unique case
Smogon doesn't do this kind of thing!
Appeal to tradition is not a good counterargument unless there are other strong reasons to oppose this idea, which there probably are, but those also don't need to be backed up by appeal to tradition. This is the subforum for changing Smogon policy.
Why is this better than Freeze Clause?
Whether it is is really up to your discretion, but it solves the ongoing Jirachi issue too and that means fewer headaches down the road. No more seriously discussing an Iron Head ban or whatever you guys are talking about would be needed and your top tier would become largely unproblematic. Also in general I think if we're gonna consider Freeze Clause then just making Freeze not happen at all sounds like a better option from a competitiveness standpoint.