You don't need upped cards to do well in T500, or any other form of pvp, asynchronous or otherwise. You could do ok with a good unupped deck against PvP2, in fact. It's not about "having 12 of every card," it's about having at the very least a decent arsenal of unupped cards (very quick to grind that, trust me), and knowing enough about the game and the strategy to play well.
For False Gods, unless you play a perfect counter you will need upped cards... but they get twice the draws and a 3x mark for free. No PvP opponent gets that.