Name trick and walking

It evolves into MissingNo

I'd assume the name takes precedence.

Probably goes in order:
Is it named and name not yet used?
Is it buddy and buddy conditions met?
Random between original three.

What do you want it to be? Or is this just a hypothetical? If you want a vape then de-buddy it evolve it and hope for the best (seems likely). If you want an umbreon or espeon, then change the name and evolve it accordingly. Either way, you have to evolve it anyways.

Vaporeon with confusion

Evolved during day you get Vapespeon.
Evolved at night you get Vapumbreon

That's the deepest shit I've read in a while...