I'm not a fan of Waluigi, I see him as a cheap ripoff of Wario. A halfassed wayy of giving Luigi some love by giving him a vilain.
I believe their is enough Mario characters in Smash (the only one I'd be willing to add would be Bowser Jr.), so I vote for Birdo. I know Birdo is technicaly part of the Mario universe but he is more associated with the Yoshi franchise for some reasons (despite the fact that he was only in 1yoshi game I think).
Ppl have been complaining on how Samus is the only representative of the Metroid franchise (forcing down our throat terrible choices like Ridley), but the same case can be made for Yoshi. Birdo is frequently refered to as the ''female yoshi'' (despite him being a guy and yoshi actualy being a girl) so It would be great to have a other yoshi representative in Smash and Birdo is the only one who I think could fit.
What?! I can't hear you over all this awsome! - Pyrrhon (Kid Icarus:Uprising)
Final Ultimate Legendary Earth Power Super Max Justice Future Miracle Dream Beautiful Galaxy Big Bang Little Bang Sunrise Starlight Infinite Fabulous Totally Final Wonderful Arrow...FIRE! - Wonder-Red (The Wonderful101)