In an early discovered demo vid of Castle Siege gameplay between Diddy, Mario, Meta Knight, and Yoshi, on many occasions it looks like Diddy's doing smash attacks. Some definitely are - right before the stage moves to the underground, Diddy is seen fully charging a smash and delivering 22% to Yoshi. It looks like Diddy does a bunch of backflips in place and pummels the foe with his hands and feet consecutively, so I think its an upsmash...
Right after that he charges what appears to be a forward smash. It doesnt land a hit, but you can really see what Diddy does. It looks like clasps his hands together and swings them around to hit with them...
Im pretty sure those are right guesses. So all that remains would be to see a probable down smash. I believe he might have done it in some of the vids we have seen, but since he hasnt charged it, its not easy telling whether or not its a smash or a tilt...
