Rillaboom is the first thing that comes to mind. It's one of the ultimate revenge killers thanks to grassy glide and terrain giving it priority. It's wood hammer also hits really hard and it has knock off, which cripples the birds that it can't really fight. Aside from the birds, it can also fight back against fire types thanks to stomping tantrum or high horsepower. It's terrain is also very helpful in helping its team from being ripped apart by powerful ground types, mostly Garchomp since it's very common
Another good one is Ferrothorn. It's still one of the most annoying Pokemon to deal with. It's spikes and rocks are no longer what they used to be thanks to boots but access to knock off usually remedies that. It also has thunder wave which only adds to the level of annoyance this thing has and its trademark leech seed is still one of the most annoying things to switch into
Tangrowth is another Pokemon that's useful in ou. It's biggest use is that it completely stuffs offensive Garchomp that lacks fire fang, stops the rain barracuda, which unlike Ferrothorn, does not drop to close combat and has longevity that makes Toxapex proud
Tapu Bulu is another option to take but since it's slower, it's mostly outclassed by Rillaboom. It also doesn't have grassy glide unlike its gorilla competition plus its more vulnerable to poison type attacks
Amoonguss is another grass type that has a niche in ou, namely spore as sleeping a Pokemon is always gonna be useful. It also absorbs toxic spikes from the annoying Toxapex and like Tangrowth, it has incredible longevity
Venusaur is also somewhat viable in ou however it is solely restricted to being the sweeper on sun teams as it does not offer anything else outside of it
The last one is Zarude simply because it can slow down the attacks of Spectrier. Really, anything that can slow down Spectrier is something worth considering due to how big of a menace it is
Source: https://www.smogon.com/forums/threads/ss-ou-dlc2-viability-ranking-thread-read-post-235.3674058/
