Ever since Super Smash Bros. Melee, Pokemon has always had a solid four fighters representing the franchise. The usual veterans being Pikachu and Jigglypuff began in the first Smash game on the Nintendo 64, they returned in Melee and two new names made their debut in the forms of Pichu and Mewtwo. As for Brawl a similar scenario with the newer faces ended up being Pokemon Trainer and Lucario as the big name players to hit the Smash Brothers scene from Pokemon which as always has been a very popular series in gaming, television and even movies respectively.
I feel something similar is going to happen with a fifth generation rep in the form of Zoroark. A shape shifting Pokemon who takes on the likeness of her enemies as an attacking and defense mechanism. Maintaing her high level of popularity over the last three or so years, her inclusion as a newcomer seems very likely when talking about new debuting stars to the roster.
That now brings us to the multitude of fans who want Mewtwo to make his return to Smash Brothers, especially that he now has a recently revealed new form known simply as "Mewthree" for Pokemon X and Y. Which could make for a rather exciting return for him to the series and would put a new twist on how he would end up playing out.
Last but not least if Pokemon Trainer does return, I hope it ends up being a more recent trainer with a group of Pokemon from the last generation or two. Even a Team Rocket villainous trainer or two would be very interesting too see. Either of these two new possible trainers would of course come with their own new set of three different evolved level Pokemon.
To hear more of my opinion on the subject of the next Pokemon representative in Super Smash Bros. 4, please watch the video below.