I remember back when Gen 1 first came about when I was really little. Just about every kid picked Charmander [I was an oddball and was more a Bulbasaur fan but I digress]. Charizard's popularity is still strong with this generation and the newer fans as well thanks to the likes of the Gen 1 remakes and many many other things not to even mention the anime.
Loved that generation as a child. The only one that I liked more was Gen 2 (though I also remember Gen 3 a lot). Also had my favorite Pokémon anime season. A big reason why I want Mewtwo so much is because of my nostalgia for Gen 1 (and not because of Melee)
Y'know, despite not wanting cuts in any form, I'd almost prefer Charizard just be PT's only Pokemon. It'd probably make him more viable, just not having the stupid Stamina mechanic, and would make transition to the 3DS potentially easier. (If there's even really a problem, aside from a fan-speculated one.)
However, for the sake of the unique character gimmick, all three should stay.
I'm a big fan of the Pokémon Trainer and would dislike to see any cuts out there. If Pokémon Trainer stays, the stamina mechanic definitely needs to go. To work around the 3DS limit, they can make it to where you can only have one Pokémon out for the match. This can give them the opportunity to change their move sets a little as well as give them individual Final Smashes. If having the Pokémon Trainer is too big of an issue, then separate Charizard, Ivysaur and Squirtle into their own slot.
This looks like the most realistic roster in my opinion. However, people think that Snake might be cut from Sm4sh due to lack of rights to include him in Smash4. Is it true that Snake is an exclusive SSBB character?
We don't know this yet, but out of all the Brawl veterans, Snake is the one in the most danger of facing the axe.
The thing is that four third-party are very unlikely to occur. Mega Man is already in and Pac-Man is all but guarantee to show up at this point, which gives us two. Then take into account a very distant off-chance that we get a third new third-party or a much more likely possibility of Sonic returning and that bring us to three. Four doesn't sound too implausible to most people, but we have to remember that Sakurai is extremely conservative with adding third-parties. He considered having up to three third-parties in Brawl, but we only ended up with two. Right now, there isn't much reason to believe that limit has been expanded. There's also no guarantee that guests from the past game gets to return and if guests do get to return, Sonic will get first priority because of his supermassive popularity in Brawl.
Nothing definitive, but I think Snake is not coming back.