In my experience its actually rather hard to even beat computers in Smash with the WiiChuck.
standard controls are terrible but if you map them well it's not bad, I used to use this
tap jump off
Z - shield
C - special
d-pad - smashes
A - attack
B - jump
A+B - special
1/2 - grab
only thing I really lose with this is instant neutral air/out of shield and it makes B reversals really difficult because pressing a button with your left trigger while inputting directions makes it less accurate especially with that very light controller...it's also more time consuming to wipe your hands of sweat, I always had to use almost the whole platform invincibility time to do that. I played MK, marth, and snake and my MK and marth were fine with this, I can't play snake with wiichuk at all though