I touched up my OP for that, I was going by Adamant / Modest in case people go for X-Scissors or a Special option for the final slot. But yes, Brave is probably the best option since two out of three moves are physical, but I added Quiet as well since Vacuum Wave could also stand to benefit from it. And Revenge killing is that's set's main function anyway, and it tends to do that quite efficiently.
Originally Posted by Zachmac
Agreed, 85 Base Speed is too high from Trick Room. There are tons of pokemon that are slower than Toxicroak, and will outrun him with TR active. Plus all of those Psychic types that he used to be able to knock out with X-Scissor can now outrun him with it. While I'm on that note, I should add that Reuniclus is an ideal counter due to its bulk and ability to easily do a TR set up and kill.
This is a signature that doesn't eat up an absurd amount of space.