Just to bury this, and I know what I’m talking about…
Last I checked, at Evo, button mapping is allowed, but you’re not allowed to have more buttons total than the game allows. Meaning, if a game has 6 independent buttons, like almost any Capcom fighter, if you want a mapped button, you must sacrifice one. Much like Fanatiq, when he plays MvC2, he loses his Assist 1 button to have a 1-button dash.