How does Inkay's evolution work in-universe?

Or maybe Inkay just flips upside down when it feels like it's time to evolve. Sorta like in the anime when Ash's Caterpie covered itself in String Shot when he was going to evolve.

Until we see how James's Inkay evolves, I'm sticking with this one.

IF we see his Inkay evolve. Malamar's portrayal of its abilities could end up making the TRio too powerful in terms of plot. The only way I can see that happening is if James' Malamar ends up constantly disobeying him. Either that, or It'll try to become the group's new leader, which Jessie might not be happy with...

Actually, the latter sound hilarious. Make it happen, writers!