i totally forgot i promised to test the PS2 controller for this, a user PMd me about it so i decided to test it out, but he asked for melee, so i tested melee and brawl.
melee :
dash dancing was fine. no problems there. i was able to do light shielding. just gotta press L/R2 lightly. not as easy as gc L/R, but its possible to do it. not hard at all. R3 functions just as well as the Cstick. L1 and R1 work as grab, so its like an extra grab button. its a fine substitute for the gc pad.
brawl:
was able to dacus with snake, took some getting used to but after a few tries i was able to do it almost as well as i do with gc pad. was able to glidetoss with zss. L1 also mirrors R1 so whatever u have set to Z will be LR1.
clicking the analog sticks did nothing in either game. overall not horrible. quite comparable to gamecube controller. if you got used to it you could probably be just as good with a ps2 controller. moreso in melee it felt closer to gc controller