Of all the characters, Charizard is the character I have the most hope for in terms of balance and design.
I think he should be a character who is both super strong and super fast.
If that sounds crazy, one has to first observe Charizard's proportions. With relatively short arms and trunks for legs, he has the worst reach out of any heavyweight character. A very big character that has to get very close. It's not like DK, who extends his already long arms and legs to get the most out of his reach.
Charizard is of course highly mobile and already has some agility compared to other heavier characters, so I don't expect him to be as strong overall as Bowser. That said, I think being respectably fast on the ground, in the air, and with his attacks is perfectly okay. At the very least he still has his nair and stuff to put that big body to his advantage. That Flamethrower range will help to build damage in any event.
Don't know why I care so much. I guess because, while a dragon isn't special, he is super unique compared to the rest of the roster. So much potential, from both a gameplay and aesthetic standpoint, to be something really awesome.