1. Find Wolf in the Iseki Ruins Stage in Subspace Emissary
2. Complete 450 Vs. Matches
You can find Wolf in the "Iseki" Ruins Stage in Subspace Emissary. When you are being lowered into the pit, skip the first door you pass. Enter the second door at the bottom instead. Obviously it will take a LONG time to clear 450 Vs. battles. I would only do it this way if you don't really care about unlocking your characters. You will be playing a Vs. battle a couple months from now and be surprised when this challenger approaches. If you don't want to wait that long, I'd look for him in Subspace Emissary. I don't really know enough about Wolf yet to give any good advice on defeating him. I will post more when I get some experience with him.
Every man dies, but few truly live. Live your life to its fullest, every day as if it were your last.