What happens if I try to use Ho-Oh EX's "Rebirth" Ability but my bench is full? Is the Ability used up, or is it not used and I can try it again later after I have some space on my bench?
If you know the Ability will not affect the game state, you cannot use it. If your Bench is already full, you cannot use Rebirth.
Source: TPCi Rules Team (2016-06-09)

Relevant cards

Note: All applicable cards may not be listed below.
BW6_22
BW6_119