What Pokémon should have gotten an evolution but never did?

There are so many Pokémon that feel like they were meant to evolve but never did. Some even have clear counterparts that received evolutions while they were left behind. For example, Magneton got Magnezone, but Dugtrio never got a similar third stage, even though it seems like it could have.

I also think more Pokémon should evolve by learning Ancient Power, like how Yanma turns into Yanmega. Octillery, for example, could have a prehistoric-inspired evolution that ties into its origins. And what about a male-exclusive evolution for Gothitelle, similar to how Gallade branches off from Kirlia?

Which Pokémon do you think deserved an evolution but never got one? What kind of evolution would you give them?