Sceptile Leaf Blade
Nighttime Guardian
What about them? I meant having an Ability that will automatically set up Trick Room.
They're among the best Trick Room setters of this generation, although Bruxish, Stakataka, and Comfey are also quite good for their own reasons. An ability that'd set it up would be interesting, although I think it could be overpowered. Trick Room is one of the strongest moves in the game, it's negative priority for a reason and there are no items to extend it (unlike terrains or weather). Maybe it'd work if Dialga got such an ability, it'd fit it quite well and it's among the slowest of legendaries, and Dialga currently isn't really top tier among legendaries anyway. The thing about rooms, unlike weather or terrains, is that you can't overwrite them with a different effect, and Trick Room is powerful largely because of the way pokémon are balanced. Faster offensive pokémon are generally very frail (see Greninja, Tapu Koko, Raichu, Pheromosa, Alakazam, Lucario, Gengar, etc.) while slower offensive pokémon tend to have a lot more bulk to compensate for their lack of speed (see Snorlax, Wishiwashi, Incineroar, Mega Ampharos, Alolan Muk, Alolan Marowak, and so on), and pokémon used in Trick Room tend not to invest any EVs into speed either so they can also invest a lot more EVs into bulk. This means that not only do they get the speed advantage in Trick Room, they also have a significant bulk advantage. Trick Room is currently balanced out by being negative priority and it can be stopped in several ways like Taunt, Fake Out, or by nuking the Trick Room setter before it manages to set up, all methods that wouldn't work if it was an ability to set it up instead of a move. A Trick Room that manages to go up and is played well is incredibly difficult to stop for faster teams. Last year I played Trick Room under VGC 2017 rules in the online competition of April and reached the top 10% of participants with it.