Finished my second run! Here's what I've got:
Snivy: Ew. Horrible coverage (unless you do some serious shard hunting), average stats, and poor match ups against most of the Elite Four and Gym Leaders. Coil is a neat move I suppose, but it's not enough to save Snivy from mediocrity, especially since using it means you need to give up using superior pokemon in Tepig and Oshawott. Low
Rattata: Maybe it's because mine was in the top percentage (Adamant Nature with 30 IV Attack), but Rattata was actually decent. It evolves early, has a nice early STAB in Hyper Fang, and learns most of its best moves through level up or TM. As in most games, it began to fade of later, but never so much that I actually felt the need to drop it from the team. Super Fang is awesome too, if your team has trouble with a specific pokemon. It's biggest problem was its ho-hum usefulness against Gyms because of its Normal typing. In a nutshell, Rattata won't let you down as long as all you're expecting is a serviceable Normal type. Mid
Klink: To be clear, Klingklang was good once you finally got it. Automatize + Gear Grind is really all he needs to thrash his way through the Elite Four with the obvious exception of Marshall and Shauntal's Chandelure. That's nice and all, but in order to get to that point you need to baby the weak Klink until level 38, then put up with the mediocre Klang for another 11 levels. This would be tolerable if Automatize didn't come at level 52 for Klang and level 54 for his evolved counterpart. If you're not over leveling, that means you'll only be able to use Klingklang to his full potential against the Elite Four and perhaps Victory Road. Throw in his uselessness against most Gyms he's available for and it just wasn't worth it. Low
Banette: Banette was kind of a mixed bag. On one hand, it's very strong. On the other it's both frail and slow. Sucker Punch and Shadow Sneak lessened this problem somewhat (if you catch one at level 32, in the Strange House, it will already have the latter and be 2 levels away from the former), but didn't hit quite hard enough for reliable KOs. Banette's other problem was its horrible move pool. No good TMs besides Shadow Claw, and no coverage moves at all. Even so, Banette was fast enough to outspeed a few things and OHKO with Shadow Claw and could usually take one hit if it couldn't and finish his opponent off with Shadow Sneak. Mid
Koffing: Koffing really surprised me. I though it was going to be much worse than it was. It comes at level 12, which is a bit low, and doesn't have any good moves. Luckily, you get Venoshock from Beating Roxie, making him much more viable right away. Combined with his high Defense, he can easily tear through the early game with just Poison Gas and Venoshock. Right before he evolves he also gets Sludge Bomb, and can learn useful TMs like Thunderbolt, but those come too late to be of much use. He also boasts great defensive typing when paired with Levitate, and can use this to his advantage against Clay, Burgh, and Marshall. Overall, Weezing ended up being a solid member of the team, although his poor STAB and lack of coverage until late game was annoying. Mid
Theory Vote
I'd bet that we can all agree Umbreon is Bottom. It has a horrible movepool and horrible offensive stats. Foul Play was a huge boost for it, but that means you need to grind for Shards and you're still stuck with the problem of no coverage moves. It just doesn't offer anything over other Dark types besides bulk, but no one likes Walling things to death for an in-game run. Use your Eevee for something else.
