In general, we banned most of the super meta cards like Nova, Graboid, Fractal, Dim Shield, Fire Bolt et al, to start with, if the rules did not prohibit them already. Beyond that, we would assess common thought processes relative to the meta (IE: Does this meta support rushes heavily? We should ban Immolation if it does.), and cap deck size if big rainbow stalls (IE: THE DECK) are a viable option, as these decks make tournaments very unfun. I can't speak for other PvP sections, or the present Tourney section, but when I was a TO, this is how things were done.
