In the game itself, the Oracle is everything.
The FG challenges are obvious, and sometimes its cooler to challenge yourself by checking their deck out and working off that, rather than a random anti-FG. For me, that means a various deck with aflatoxin, either on my side with Bonds, or on theirs with Solar Shield, or Vultures, UGs or something.
Also with 3 game pets, you can play around with those. If it's Dune Scorpion, you are in huge luck, but even then, you can get some pretty cool decks going with Schroedingers, Chrysaora, and sometimes even Sparks.
And obviously, the external PvP is great, the more restrictive and challenging the better.