From Bulbapedia, the community-driven Pokémon encyclopedia.
The A-B-C Islands (Japanese: イロハ諸島 Iroha Archipelago) are an anime-exclusive group of islands off the coast of Hoenn that appear in the episode The Evolutionary War!.
Trainers that live on the islands have a rivalry with each other: one group believes Huntail are stronger and another group believes Gorebyss are stronger.
Island A has a Pokémon Center which is also home to a school. On Island B, DeepSeaScales can be found to evolve Clamperl into Gorebyss, while on Island C, DeepSeaTeeth can be found to evolve Clamperl into Huntail. Racing their Huntail and Gorebyss between the islands, as a result, is a common occurrence.
- The reefs off the shores of these islands resemble particular katakana characters. Island A's reefs make an I (イ), Island B's make a Ro (ロ) while Island C's make a Ha (ハ). This (along with the name of the archipelago) is a reference to Iroha, a traditional way of grouping kana characters. This is somewhat equivalent to western ABC's.