You'll need to choose a wrestler with the Blackout Payback, such as Sting, and play a match. You can do this on easy and Iron Man is a good way to not lose the match accidentally.
Get your finisher loaded up then take damage until your Blackout Payback is ready. Press
and
together to activate the payback. There will be a cutscene where the arena lights go out, you will appear behind your opponent. As soon as you see the
available hit your finisher and the trophy will pop.