The main argument for Landorusi getting banned was "you don't know which set it is!" and that the physical and special sets needed to be handled entirely differently. Wouldn't be a problem if PS was a more proper simulator though, because Sheer Force Landys are always in Dream Balls and Sand Force Landys are never in Dream Balls.
That wasn't the main argument, physical Landorus didn't even factor into the decision.
It was banned because it significantly restricted defensive teambuilding. It's list of checks and counters was practically nonexistent, and it could bypass most of them with U-turn. It pretty much invalidated an entire playstyle (stall) by itself.
I didn't get voting rights for the Keldeo test, but my thoughts mirror Roc_Raida.
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