you forgot something about the .2 that you have to also somehow change the sprites, lol
(and what type of variable? enum? if so, i need to know what folder you make your enums.)
Viewing post in ChrisFurry's Barebones Sonic Engine comments
states and animations are in the enum,
for super you would literally just add 'superform = 0' to the create event.
i suggest you start reading up on this GameMaker Studio 2 Language Reference
Very simple. (sorry i didnt get notified of this one for some reason)