>>30951747The Pokemon on its tail is a Shellder. It evolves with Slowbro.
The crown on Slowking's head is also a Shellder.
It's been like this since the beginning.
It's just not its own Pokemon, because it is explained that the symbiotic relationship changes both Pokemon. If the thing falls off, Slowbro turns back into Slowpoke and the Shellder turns back into a regular Shellder. This is why its not its own Pokemon:
Source:
Yellow: Lives lazily by the sea. If the Shellder on its tail comes off, it becomes a Slowpoke again.
Y: When a Slowpoke went hunting in the sea, its tail was bitten by a Shellder. That made it evolve into Slowbro.
It evolves at Level 37 on its own without Shellder, though, and Slowking evolves with a King's Rock. This is probably because of some limitations about merging Pokemon that were there at the time... and it's just since been grandfathered in.
