Z+direction for specials. D-pad to move. Do X+down in midair to use D-air. S for shield, down while shielding to spot-dodge. A to grab, X to jab.
The remix by Scratcher1002 is Version 0.3. V0.31: Revamped fireballs. They fall to the ground faster. Range nerfed to two bounces. Physics engine "broke": jump height roughly halved. I think the fireball physics somehow made themselves apply to Mario?