Let’s say, Raichu Alola got an evolution with an ability called Supra Surge Surfer of Apocalypse. That ability would rise all stats by 3 stages if sun and electric terrain are active. That example might be a little far fetched but, if that mon was too powerful for Ubers, due to the easiness of setting Sun and ETerrain but very weak in OU due to the lack of good setters, could the Ubers council ban Gorochu-Alola or its ability without affecting OU?
The question is a bit confusing with the way that you worded it (banning something without affecting OU?), but the answer to your question would probably be yes. It'd obviously depend on how strong the mon is, if that specific pokemon doesn't have realistic counterplay under the very unique conditions for it to prosper, there is a good enough chance that the council would quickban it. However this would only be if the pokemon itself becomes overbearing due to the ability, an ability ban almost never happens unless it is proven to be broken on multiple users. (Denial cases include stuff like Libero on Cinderace, or Gorilla Tactics on GDarm. Abilities that have been banned include Shadow Tag and Arena Trap, which made pokemon like Trapinch actually viable due to the overbearing nature of trapping.).
Generally smogon tends to lean on Pokemon bans, so in this theoretical instance, it would ultimately depend with exactly how strong this theoretical Raichu evolution if both sun and E-Terrain are up.