You absolute madman.

I figured this was the case. For years I’ve rationalized Slowbro/Slowking’s Shellders as just having mutated as a result of evolution and being attached to another Pokemon, but man that explanation is kind of shaky. It’s a shame they didn’t make this Pokemon a thing. I could also see it being a middle evolution…

Everyone already mentioned it, but $$$$$ and connectivity.

But there’s also an in-universe explanation of each individual game cartridge being its own pocket universe in the greater Pokemon Universe, furthered by revelations in XY, ORAS and Sun/Moon. Which is pretty cool if you think about it.