I'd have to say, in all honesty:
Wario
Squirtle: Wario is, basically, a stronger, more manuverable, heavier, better-at-killing version of Squirtle. Squirtle's at either a disadvantage or major disadvantage (because of range, I'm thinking just disadvantage, but this is debatable.)
Ivysaur: Ivysaur has a giant range advantage over Wario. She's also a great anti-air character, and Wario loves spending time in the air. They both rack up damage quickly against each other quite well. However, Wario has no trouble getting Ivy off of the edge, and once off of the edge, is excellent at gimping. I'd say, because of that, neutral.
Charizard: Charizard is big. Wario has no trouble racking up damage. Considering his aerial manuverability, he's also good at dodging Charizard's attacks and retaliating. Zard definitely has a range advantage, though. Charizard and Wario are both able to gimp each other if played right when fighting off-stage. Overall, I think that Wario has the advantage.