Waluigi. He’s a kickass Mario universe character that I find to be an excellent choice in whatever Mario game I play. He’s got the good looks, the taunts, the evil but slightly unlucky streak… and did I mention the taunts? He’s absolutely flabbergastingly excellent in pretty much everything! Make 'em Waluigi Golf/Tennis/Kart 'cuz Mario’s got nothing on him!
Tennis? His full-body style is absolutely fantastic!
Golf? Solid drive, control AND spin!
Kart? His wheels ain’t bad and I like the special…
Party? Heyyyeven though you can’t cheat, he does seem to win against impossible odds 
GIMME HIM IN SMASH AND I’LL SHOW YOU FEATHERWEIGHT KILLING SPREE! And give him his own game too, sheesh!
Now Luigi… hmm… He doesn’t have a dime against his Wa-pposite! But I’d still pick the underhand bro over Mario! Ha! (I don’t like Wario that much either!)