I haven't played any other character but Suicune simply because I haven't lost a single match with him yet. Almost 100 matches strong.
Are you trying to play as him in a later match while he's still level 1? That might be why.
I built him by solely focusing on his Special technique thingy (the one above the support skill) and attack. His best moves in (still trying to remember the names here) the close combat battle mode is up blizzard, back barrier, grabbing into a combo, down attack where he uses his tail to puncture the enemy, and stalling.
When in the more open space mode (the mode that starts when you are in a open field) stalling, hyper beam, sky hydro pump/water gun, air blizzard, side water bubble thing, back surf, grabbing into a combo, and some sort of water drop ability are the best.
My friend described Suicune best to me when I was chatting to him on my phone, he's practically the Pokken Equivalent to Villager in terms of his moves. You have to set up some things, get timing right, be careful when getting up and personal, but with the extra ability of wrecking shit up when activating special mode since that was your focus.