Honestly the only thing I don't like about Pokemon trainer is the annoying mechanic where if you don't switch them out, the Pokemon get weaker, although I'd like to see Squirtle's fully charged water gun actually do some damage this time. All of them have their own strengths, although I'd say Ivysaur=/>Squirtle>>Charizard overall. Ivysaur can rack up crazy damage and is great at spacing as well, whereas Squirtle has tons of speed and an awesome aerial game. Charizard is always going to feel more clunky and awkward than the other two, but Rock Smash alone makes him viable. Ivy is the best of both worlds in terms of damage and kill power though. Besides, nothing feels more satisfying than 1 shotting someone at 20% with Ivysaur's uncharged Up Smash (yes I understand this is impossible to land in online tournaments).