I played exclusively on Showdown with PU/RU formats, so my experiences with it are pretty biased with other crappy mons lol.
Rimbombee wasn't actually that bad in the higher tiers from what I can recall, they were considered to be the fastest Sticky Web user in Gen 7, so that was a niche user you could have even in Ubers. They also had access to Quiver Dance and Fairy Type, which was allowed to setup against most dragon users. You could even be a madman and run Ribombee with Oricorio for DOUBLE QUIVER DANCE ACTION in Doubles, as long as your opponent wasn't running a Rock Slide lead (impossible).
But yeah, in the weaker formats, Rimbom was pretty good, but that's mainly because it could take at least one hit before being disintegrated most of the time.