Smash Bros. does have some Pokémon characters that you can use, like Charizard and Greninja. But, there aren't enough playable characters for a Pokémon-centric fighting game. Enter mods.

Thing is, Smash Bros. games do include the character models for plenty of Pok√©mon, for use whenever you throw Pokeballs in matches. Sleepy Jirachi seems to have gone ahead and made use of these character models for a Brawl mod named "Pokebrawl," and while it's only in beta right now, it already looks great. I say that as a huge Smash Bros. fan, though‚ÄĒthis appeals to me more than a Pok√©mon fighting game in the style of Tekken. I'm also a fan of the character selection here: you've got obvious Pok√©mon, like Blaziken. But there's also interesting additions like Rotom, Jirachi and Darkrai:

Right now, the creator is looking for collaborators to help with the modding‚ÄĒhere's hoping that some people sign on, because the project looks really cool.