I guess this is the right topic to share that the platforms that split the biomes in Indigo Disk can actually create some confusion on met location, specially when catching Pokémon while standing on it.
I've just caught a wild Seel while standing on the platform that split Polar/Coastal biomes and its location is stated as Coastal Biome, but the Pokémon is only native to the Polar Biome. If you whistle, the Pokémon will follow you and stand on the platform as well, if you start the battle at the side the other biome music is playing and catch it, the Pokémon will display its met location corresponding the music area.