I wouldnt say that this ability is a dubble edge sword he doesn't choose the game, if it is taller-monster he would lose to anyone taller then him, if it's shadow-monster then if he touches his shadow he gets hurt. This is the closes ability to a hax ability without being one I wouldn't expect anything less from a senior captain, especially someone who has been given such praise.
In “Kagefumi Oni” if you get your shadow stepped on you lose, in “Taka Oni” if you’re up higher than (the Oni) you win if you lose you die and if you win you live
These are based on childhood games called “Kagefumi Oni “ and “Taka Oni” which are variations on the standard “Oni Gokko” (Oni Gokko being similar to Tag):
Kagefumi Oni, one person is the Oni and chases around others trying to step on their shadows. If you get your shadow stepped on then you’re “it” (the Oni).
Taka Oni, is like normal Oni Gokko except that the way to avoid being tagged by the Oni is to be in a higher position than the Oni (like on the jungle gym, standing on a rock, etc.). You can only stay in one high up place for a certain amount of time before finding a new one. If you get tagged by the Oni then you’re “it” (the Oni).
Iro Oni is usually played by having the Oni picking a color and the other players trying to figure out that color and touch something of that color. Those who haven’t found and touched that color are chased by the Oni (and whoever gets tagged becomes the new Oni and has to choose a new color). If the Oni can’t tag anyone then they have to choose a new color.
If you remember Taka Oni was the attack Shunsui didn't get to pull off on Starrk, and when he tried to do it he already had the higher position meaning he would have won that game.
This leads me to believe that this ability that he is using is one of his Shikai. Bushō Koma is his distraction ability to help him pull off the rest, Kagefumi Oni and Iro Oni must be the other names of his abilities.