Currently, Eevee has 8 different evolutions. Some might say this is just too many, but I would respectfully disagree. Eevee could use a few more evolutions (maybe even one for every type). There are more than a few types that have not been assigned for one. Here are just a few types that could yet have an evolution form for Eevee.

1. Dragon

Some of the best and strongest Pokemon are of the Dragon type. It would be interesting albeit unusual to see Eevee turn into a slightly larger, scaly version of itself. Give Eevee some wings, the cat-like eyes, and other features. Another interesting option could be to make male and female versions. The sky is the limit with what this evolution would look like, however, I could better imagine this particular Pokemon looking more like Spyro (below).

2. Steel

Steel has always been one of my favorite types ever since it came out in the second generation of Pokemon. It would be interesting to see Eevee maybe have a type of armor, either on the scale of looking like a gladiator or like a robotic version of itself. Not really sure how a Steel type would work, but it would be interesting nonetheless.

3. Bug

This is a bit of a stretch I think, but it could work given that it is pulled off the right way. The key here is that they put some thought into it. I have often criticized Pokemon (the company) for having Pokemon that make it seem like they ran out of ideas. Hopefully a Bug type Eevee evolution would not fall into this group.

4. Fighting

There are one of two ways that they could go about making this one: One that has an emphasis on kicking, perhaps having larger hind legs or two, having an evolution that stands on its hind legs and has the ability to fight in either way (standing on two legs or on four). The only problem with this type is the problem that would exist with a lot of these would be the logistics of how it works.

5. Rock/Ground

Rock types have had traditionally thicker exteriors such as Golem. Why not give Eevee the appearance of a Rock type? Not full on The Thing mind you, but at least some features of Eevee being more rough and gravelized.

6. Normal

All of the Eevee-lutions have changed the basic appearance of Eevee. What if Eevee had a form that was just a bigger version of itself? The only challenge with this one might be by what means they evolve. What has originally started with using various types of stones went to leveling up around certain areas. Creating different evolutions will take a great deal of thought and creativity, which hopefully developers can channel.