Eevee is so useful... when evolved of course. If you don't evolve him... uh... well, let's try something...
Set name: I'm cursing
Ability: Adaptability
Item: Eviolite
Nature: Careful
EVs: 252 Hp, 252 SpDef, 4 Def
-Return
-Curse
-Wish
-Bite/Heal Bell/Baton Pass
Eevee's special defence isn't that bad after the boost gained from Eviolite, so a cursing set seems somehow viable. This EV spread gives you 314 HP, 205 Def and 376 SpDef, good for Curse. Your special defence is quite nice, infact on the special side you're just around 1% less bulky than max special defence Dusknoir. Return is your best attacking move. Thanks to Adaptability, it's STAB boost becomes x2 instead of x1,5 giving it 204 BP, wich corresponds to a 136 BP move with the traditional x1,5 STAB boost. Curse boosts you attack and defence, making you sturdy and powerful. Wish is your only way to recover your HP, so is pretty much necessary. It also allows you to pass wishes to your team mates. Yes, they are not big wishes like Vaporeon's, but 157 HP recovered isn't that bad. For the last moveslot, Bite covers ghosts, as they just completely own you. You can forego Bite if you aren't afraid of ghosts (you can use a Pursuit user to kill them) and use some support moves. Heal Bell supports you team and gets rid of statuses like poison and burn that would hinder your attemp to sweep. Baton Pass on the other hand works well with both Curse and Wish. If something that counters you shows up, than you can Baton Pass your curse to an appropriate counter, or you can Wish and, assuming that you're slower than the opponent and that it won't be able to KO you, you can take a hit and Baton Pass thus bringing in a team mate for free ad get the wish.
The EV spread gives you maximum special bulk, which can be abused nicely with only one weakness to a usual phisical type. Max HP is necessary due to general bulk and better wishes to pass, but you can split the remainig EVs between Attack and Special Defence make Eevee more powerful so that you don't need to reach +3 Attack to start doing some damage. Remember to use a Careful nature instead of Adamant unless you're going to invest almost completely in the Attack, as your base SpDef is higher than your Atk, so you will get a more efficient spread with a Careful nature.
Other options
Double Edge and Last Resort are alternative STAB moves in the place of Return. Double Edge is powerful, but the recoil is very bad considering your low HP, no leftovers and Wish that isn't as reliable as Recover, so it's not advisable to use it. Last Resort is crazy powerful, but you can use it only on the forth turn. You could use Protect in the last moveslot to fix it a bit and to make Wish more reliable, but it only has 8 PP, so is generally worse. As just said, protect renders wish more reliable, but makes you less useful to your team.
Team mates
As your main attack is normal type, you need to take care of ghosts, rocks and steels. Ghosts can be killed by a Pursuit user. Spiritomb is very advisable, since it easily takes on both ghosts and the fighting types that threaten you with their powerful phisical super effective moves. It also benefits Eevee's Wish support. Magnezone/Magneton are good partners too as they trap and kill steel types thanks to Magnet Pull.
Counters
Ghosts, rocks and steels easily stop your... uh... rampage? Well, Eevee is easily conterable unless it gets at +6 attack and defence. Fighting types will destroy you with their STAB attack, hazers/p-hazers will render you almost useless, phisical walls should do a fine job too. Eevee doesn't pack leftovers and has wish as a recovery move, so it's very weak to passive damage. Sandstorm, Hail, burn, poison, Leech Seed will all hider Eevee a lot expecially burn which will cripple it completely.
UU Wallbreaker
Flareon @ Life Orb
Flash Fire
Mild
144 Attack / 92 Special Attack / 164 Speed
Fire Blast
HP Grass
Superpower
Work Up / Toxic
Speed outruns most Milotic and Cresselia. After a Work up Superpower OHKOs all Chansey after Stealth Rocks. HP Grass OHKOs all water / grounds and 2HKOs Milotic and Slowbro (and you easily survive a Scald). Fire Blast does 98% minimum to Hitmontop and 99% to Spiritomb. Fire Blast 2HKOs Arcanine if it runs intimidate and Superpower 2HKOs if it uses Flash Fire and Stealth Rocks are down. Fire Blast easily 2HKOs Cresselia unless it's Specially Defensive. You can drop Work up for another move but this is pretty much THE entire movepool. POssibly Heal Bell if status moves are utter DICKS to you or Shadow Ball is you want a little more damage against.. Slowbro? Toxic could actually work to scout out and damage counters like Moltres / Milotic and Slowbro. I guess you could always run this in RU but no one cares about RU.
Have fun.
This set is very cool but the EV spread isn't the most efficient one. When you're pumping up with the EVs two stats (unless you need to completely max out one of them) always use the nature that boosts the higher base stat of the two. You used a mild nature while you should opt for lonely. You said HP [grass] so i guess the IV's should be 30 SpAtk and Def and 31 in everything else. With this IVs, your EV spread 144 Attack / 92 Special Attack / 164 Speed with mild nature gives you this stats:
HP: 271
Atk: 332
Def: 139
SpAtk: 272
SpDef: 256
Spe: 207
An EV spread of 94 Attack / 252 Special Attack / 164 Speed with same IVs and lonely nature gives you this stats:
HP: 271
Atk: 351
Def: 139
SpAtk: 288
SpDef: 256
Spe: 207
As you can see, my spread is more efficient and gives you 19 more Attack and 16 more Special Attack, it's like having invested 140 more EVs (136 counting a jump stat in the special attack). I think that you should modify a bit your EV spread. Maybe just taking this one, or maybe investing more in Speed as you already achieve a lot of good KOs. Anyway, good job. This is a very cool set for a very good pokemon