From Bulbapedia, the community-driven Pokémon encyclopedia.
Gloom can evolve into either Vileplume or Bellossom through different methods.
This is a list of Pokémon which evolve differently depending on certain conditions. To date, no Pokémon whose pre-evolution has a branched evolution also has a branched evolution; Wurmple is the only Pokémon with a branched evolution whose evolutions can evolve again.
Most evolutionary families that have a branched evolution have only two evolutionary stages, although there are several families for which this is not the case. Many evolutionary families with branched evolutions only gained a branched evolution in a generation after the family was introduced; for example, Kirlia was introduced in Generation III along with its evolution Gardevoir, and Kirlia's alternate evolution, Gallade, was introduced in Generation IV.
Pokémon that have branched evolution