Is there a way to padhack a gamecube controller to work on a ps2? Or else make an adapter gamecube to ps2
theoretically yes, it is possible.
Would I just wire ground to ground and button to button? I’m guessing analog isn’t possible.
Analog should be possible, they both use the same type of analog pots, there may be some deadzone issues though. Also you’ll need to at least wire up a tac switch to select (or maybe Z?). You’ll also need them for L1, R1 (if you wire select to Z), L3, and R3 if you want those buttons as well.