Depends. If we're comparing them based on their respective series' then I'd say Playstation Allstars because of Dante (though it would be a very long and fun to watch fight). If we're comparing them based on how they perform in the fighting games however, Smash Bros by a long shot. If you put Sheik or Zero Suit Samus in Playstation Allstars, they would break the game and be heavily unbalanced.
I take back my first statement about the respective series'. I forgot Shulk is in Smash Bros and if we're comparing them based on their respective series', he's way beyond OP. We're talking universe, time and existance altering kind of OP.