0 Speed amoonguss is usually one of the best things mainly for trick room.
I asked in the vgc discord, and this is what I got:
to move first in trick room
- Long (idk their last name lel), a well established vgc player.
This can affect a game, as if trick room is active, the most common trick room pairings can be stopped. This Pokemon can spore things, which is fun. Spore can easily change the effect of this game. Another thing it does is underspeeding 31 iv torkoal, which is something that is ran. So ye, there's that. That helps a lot with the groudon and/or xerneas mu.
Amoonguss @ Rocky Helmet
244 HP / 188 Def / 76 SpD
0 Spe IVs
- Rage Powder
- Pollen Puff/Clear Smog (I prefer Clear smog)
So, as you can see, it's quite simple. T r I c k r o o m lmao.