1) A very slow but still viable pokemon like Amoonguss
2) Anything that can waste turns such as protect (or sleep; again, Amoonguss is good for this)
3) Priority, although many TR teams have something run quick guard to block priority
4) Using trick room yourself to undo the effects
5) Running something with Imprison+Trick Room
6) Taunting, sleeping, or KOing the TR setter before it can pull off the move, though this is usually difficult since the opponent frequently runs something to deal with these tactics (e.g. mental herb for taunting, or rage powder/wide guard/whatever for people who try to target the TR setter. I've even seen someone run safety goggles to avoid sleep powder/spore.)