Re: Battle Factory
Open level was how I got the Silver.
Level 50 was how I got the gold, following up on the advice of some random person over the 'net.
Interestingly, I think around 28 wins, you get to start battling with legendaries, like Moltres/etc., but I kept dying in about 1 or 2 battles, so yeah. (Edit: This is for open level.)
That's just me, though.
Click picture for personality survey, from "The Cave of Dragonflies."