Well you gotta think, does Sakurai want more Pokémon characters than Mario characters? I mean, if you count Squirtle and Ivysaur as seperate characters, like they are on the website, that's nine Pokémon characters. Is he gonna add another one and make it ten? Correct me if I'm wrong, but I think ten Pokémon would be more than Mario characters (not counting DK characters, Wario and Yoshi), and with Mario being the main character of Smash Bros, I don't think he'd want more Pokémon than Mario characters