You could also make your own Xyz, so yeah. But Signer Dragons and Numbers Monsters need a good explanation (Your guy would probably be from Heartland if he had a Numbers, but even then, you'd likely have to wrestle them out of the hands of Yuma, Kite, and Shark.)
As far as Duels work, if it's against an NPC, everything's up to you. If against another player, it'd be collaborated (otherwise you'd have to do turn-by-turn posts, which would get obnoxious to the rest of us). I'm working on getting a sync.in room for everyone for that, but it seems to be unable to make new sync notes at the moment (and I can't find my old one). Until then, try PMing or Google Docs, or maybe even a Mibbit chat if that works until sync.in starts working again if you have to Collab Duel.
@Jay: I wish everyone nowadays were inferior to Kaiba, but the only character from the original series who can stand up to all the others of the newer series is Yami, as he was able to summon all 3 Egyptian God Cards in 2 turns, as all the other characters were yet using mechanics that ended up outdated by the more modern Dueling styles and mechanics. It's all too easy to Synchro or Xyz Summon on the first turn, even multiple times if you have the right cards, whereas pulling out even one Blue-Eyes is a bit conditional, let alone getting your hands on all three at once. Not that it's impossible. Just unlikely. Poor Kaiba's outdated. That and if you got rid of all of his illegal cards, he wouldn't even hold half a Deck. Of course, same could be said for Yami, I guess.
