Is there no way to use a smash attack by holding down the attack button as opposed to using c-stick controls? My layout doesn't really accommodate that, as you can see:
Up (also jump) - W
Down - S
Left - A
Right - D
Grab - U
Shield - I
Special - O
Attack - P
Up (also jump) - W
Down - S
Left - A
Right - D
Grab - U
Shield - I
Special - O
Attack - P