As someone with similar concerns, I thought I'd chime in on this.Well, obviously, I would disagree with this. I have yet to see a single post in this thread that actually gives a reason I find convincing why the current system does not cover both perfectly fine, much less provide a system that would cover both better. Whether they say it or not, most posts in favor of change, to me, at least, seem to be saying that something is wrong because it something just seems... off. Yeah, I admit it is a bit weird that Pinsir can be used in NU but mega Pinsir can only be used in OU. However, policy wise, it is perfectly consistent and makes sense. As others have said, we should never tier things based on where they "should" go, because there is no "should" when it comes to tiers. It may seem weird that Charizard is OU when Pinsir is not, but it objectively makes sense, and I believe that changing it would be just giving into a subjective sense of what feels right, which is never, ever a good thing to bring into this.
Edit: Also, for what its worth, I would argue that the system not being fine is not what this thread was about. The OP was clearly about just comparing the options, not necessarily saying what we are doing now is bad and something else is better.
I'll preface this post with saying that from a philosophy standpoint, if we aren't going to view Megas as just a set the base forms can run, then we should be viewing them as the combination of the base forms and the items, not just as the Mega stones. The big issue with tiering Megas by tiering the stones only is that when Latiosite, Garchompite and other similar stones inevitable drop, we're not actually dropping Mega Latios and friends into UU. Sure, you can say "Oh we dropped Mega Latios into UU, we just didn't drop Latios into the tier", but if I can't actually use Mega Latios in UU, then I don't see how we can say that it's dropped to UU with a straight face. That's like telling users that they can use our car keys but they can't use our cars: both are meaningless without the other, thus users aren't going to buy that we're letting them drive those cars.
That being said, I agree with Zarel (I think he's the first one to point out the discrepancy) that under the original philosophy stated in XY (that Megas are just a set of the base form and not their own mons) it's rather odd from a philosophy standpoint that we're banning the items and not the mons. We didn't ban Speed Boost or Protean to keep Blaziken or Greninja, so it seems odd that we're banning the items and not the actual mons themselves. Naturally from a practical standpoint of diversifying tiers, it makes sense that we don't want to ban Lucario, Mawile, etc., but we should be aiming for a method that's consistent with a philosophy on how to view Megas and practical in terms of tier stability and not needlessly banning mons. Whether we define Megas as the stones, the base form, or the unique combination of base form + item, the tiering system should support the philosophy at all times, not just when it's convenient for us.
I've already stated my issue with defining Megas as being the stones, and under the philosophy that they are just sets of the base form, if we wanted to be 100% consistent we'd have to ban a lot of mons that are only broken with Mega stones. Thus, I propose the following train of thought:
- We treat and tier Megas as the unique set of the base form + the correct stone. Even without taking the actual Mega Evolution into account, the holding of a correct Mega stone already defies certain mechanics followed by standard items (Stones can't be Knocked Off or give a boost to Knock Off, can't be stolen by Switcharoo, etc.) so it's not a stretch to define the combination of the base form + the correct stone as a different mon altogether much like the Arceus Forms.
- We tier the combination of the base form + the correct stone, not just the stones itself. Yes, this means that Mega Garchomp in UU would constitute using Garchomp + Garchompite in the teambuilder and bringing Garchomp + Garchompite into UU. Now, for everyone complaining about "abusing the base form", what abuse are you talking about? You can't use Rocky Helm Chomp in UU. You can't use Scarf Chomp in UU or Life Orb Chomp in UU. If you see one in UU, you know immediately that it's a Mega Garchomp. If you're worried about abusing a change in stats, then let's not forget that Aegislash abused changing its base stats in-battle far more than anything Mega Garchomp could do. Rather than look at this as "Mega Garchomp abusing its base form" we should look at it and other Megas as "being able to abuse having a separate set of base stats" just like OU did with Aegislash.
- If a Mega is considered broken in a tier, have the tier ban the the appropriate stone. If we've broken up the pairing of the base form and the stone, then the Mega itself has effectively been removed from the tier while still allowing the base forms to drop and maintaining the philosophy