The only debatable one therefore for me is Charmeleon. To answer this I think we need to consider the role that Charizard plays in OU. If we adopt the assumption that the vast majority of Charizards are of the BellyZard variety, which I think is valid one, and that this is the one set that makes Charizard truly threatening in OU, then I find it difficult to allow Charmeleon on the basis that, if it were allowed in, almost every Charmeleon would carry that same set (except something else over Earthquake, probably Dragon Claw) as it is probably the only way that Charmeleon is threatening or even competitive at that level.
Although Charizard is not OU, but technically BL, in my experience I've seen my fair share of Charizards in that environment, all of which were BellyZard, and appears often enough there for the need for any decent player to recognize the threat it poses. Therefore, if Charmeleon is allowed in UU, I foresee a similar approach to countering it as people do with Charizard, which signals to me OU-Lite. In short, no for me.
Even if the best set on Charmeleon does turn out to be the drummer, I am still not convinced that would be enough to see its banning.
Firstly, there are plenty of pokemon that duplicate each other's roles across the tiers. A great example is this generic moveset:
Rain Dance
~
Surf
~
Hidden Power Grass /
Hidden Power Electric
~
Ice Beam
that many water pokemon share, and with minor variations depending on metagame it can form some of the most effective sets for pokemon as diverse as Luminion, Luvdisc, and Manaphy.
While this moveset may be the most valid for many pokemon, it may still be repeated across metagames with no variation. No one raises objections to this because the pokemon are all fully evolved forms and so do not suffer from an entrenched bias.
Secondly as others have brought up before me, while Charizard and Charmeleon have almost the same movesets, Charizard may still be distinguished by typing. Because Charmeleon has no immunities, it is much harder to bring it in on a choice-predicted move, while at the same time the lower weakness to Stealth Rock changes whether the player may rely on using the rocks once or more time to halve his Pokemon's health before subbing and activating the Salac Berry.
Finally, I doubt that Belly Drum is the set that really defines Charmeleon in UU. There are, as far as I know, four Drummers in UU: Linoone, Poliwrath, Politoed, and Poliwhirl (although Poliwhirl is an NFE as well as Charmeleon, its higher speed gives it an advantage on Poliwrath that may come in handy when Drumming or Scarfing. Neutral speed nature whirl has higher speed than +speed wrath, so the lower attack on whirl may be justified by a drumming set with higher speed.) If a UU player wants a Drummer, he is probably going to go after one of these rather than Charmeleon, whose main contribution as a Belly Drummer lies in his moveset (and higher speed than Wrath perhaps, though his attack is lower than whirl's).
Given that the true philosophy of team building (a la Surgo post from the beginning of Stark Mountain or something around there) is to use pokemon to fill niches rather than to copy the stats of a successful and similar form, the best set for Charmeleon in UU is arguably not its Drumming set given the fact that other pokemon pull off Drumming better than it does. Although Charizard's stats and typing give it a premier position in OU for the role of Salac-Drum Sweeping, Charmeleon is outclassed in that role in UU, and so theoretically Charmeleon's ideal role is something more akin to niche filling than anything.
