The simple two-move combination being performed is this GIF? Shadow Mewtwo can do that all day in Pokken Tournament. That's bad. Demonstrated on Twitter and captured on video by YouTube's Shofu, the one-two punch of Shadow Mewtwo's backward-Y ranged attack and the transformative power of its Miracle Eye move combine to form an endless attack combo that enemies can't stop blocking.
It's an easy combo to pull off, just back and Y button for the attack, then back and A for Miracle Eye. Get the timing right, and once your opponent starts blocking it's all over. When a player blocks they experience a brief moment of block stun, during which they're locked in block position. Shadow Mewtwo's moves fire faster than the block stun cooldown. There's a block break mechanic in Pokken Tournament, but this combo never triggers it. It's pretty nasty.
Shadow Mewtwo does suffer damage from using Miracle Eye over and over again, but it's never enough to knock it out, leaving it with one hit point. The combo can't kill a blocking player, so in time they also drop down to one hit point. Since different Pokemon have different hit point amounts, Pokken Tournament gives the player with the highest percentage of hit points left at the end of the round a win. Shadow Mewtwo has the lowest hit points in the game, so its one hit point is better than everyone else's.
Shadow Mewtwo is supposed to be powerful, but this is a bit much. Hopefully Namco Bandai can patch this infinite blockstun out of Pokken Tournament quickly. I lose enough online as it is without having to lose to cheap exploits.