Been trying this set out in ubers. I know this isn't necessarily a "Post your great uber sets!" thread, but it is a 'mon not often seen in ubers (65 uses last month).
Jolteon @ Choice Scarf
Modest Nature
Volt Absorb Ability
EVs: Hp 90, SpAtk 252, Spd 168
~ Thunder
~ Hidden Power [Ice]
~ Shadow Ball / Sleep Talk
~ Toxic / Sleep Talk
Hits 507 Spd after CS, enough to outspeed max Deoxys-S and most CS Darkrai, unless they go max speed, which isn't often as most go 506 to outspeed Deoxys-S leads. Makes a great counter to Scarf/Specs Thunders that plague the uber tier. Thunder is the only move you should really use, as it's usual 100% accuracy and 120 BP make it very powerful. Hidden Power [Ice] is to catch DD Rayquaza who think that they outspeed you. Shadow Ball only hits Lati@s more than anything else, everything else is hit for more by Thunder/HP (besides Giratina, who will shrug it off anyway). Toxic is filler, but it can be used for walls etc, or Sleep Talk can be used over either of the last 2 to take Dark Void etc.
Damage calculations
Thunder Vs...
Scarf Darkrai
71.43 - 84.01 %
Never an OHKO even with SR, but more than enough damage to seriously hurt him. Bring a priority user and finish him off when he tries to Dark Void again. The Dark Void that you inevitably take can be lessened by using Sleep Talk.
Nasty Plot Darkrai
74.47 - 87.59 %
Only posted this to show the 2.56% OHKO with SR. Switch in on a Nasty Plot and outspeed.
Deoxys-A...
Do I even need to post this? Outspeeds all, even the CS set and OHKO's with Thunder (God even HP [Ice] OHKOs)
220/0 Deoxys Spikes Lead
70.95 - 83.45 %
An easy 2HKO, outspeeding and only allowing SR or 1 layer of Spikes down. If you're really lucky it'll Taunt first turn :)
0/6 Ho-oh
74.79 - 88.39 %
OHKO with SR (isn't anything when you lose 50% on a switch?). Even without SR, 75% on 106/154 defenses is pretty good.
248/252 Ho-oh
49.16 - 57.83 %
Still a 79.49% OHKO chance with SR. This is before a CM.
*If no SR are present and Ho-oh CMs on the Thunder then the second hit is 32.29 - 39.04 %, meaning that it becomes a 3HKO.*
6/0 Kyogre
84.21 - 98.83 %
74.36% OHKO with SR up. Jolteon outspeeds all Scarf or other Kyogre. Jolteon can actually win even if Thunder doesn't OHKO, as long as Kyogre uses Water Spout that turn. The highest % Hp Kyogre can have left is 3.29%. A water Spout from that much does less than 10%, so you can happily KO Kyogre with the 2nd attack.
252/0 Lugia
63.46 - 75.00 %
A 2.56% OHKO chance with SR. Small I know, but if you catch it on the switch it's gg and even if you stay in, all it can do is Whirlwind you out, set up Reflect, Roost (while you finish it next turn even with +50% Hp) or it can Ice Beam. An Ice Beam from the Great Wall set does 22.53 - 26.62 % back, so you're safe.
80/0 Manaphy
106.37 - 125.21 %
A definite OHKO. If you switch in on a Tail Glow then you're fine.
252/36 Mew
46.04 - 54.21 %
100% 2HKO with SR. Mew will hopefully try setting up it's Baton Pass, not Hypnosis you, or you can rely on it's 60% accuracy if it does Hypnosis.
6/0 Mewtwo
59.32 - 69.77 %
A guaranteed 2HKO even without SR. Jolteon outspeeds all but the Scarfed Mewtwo, so you may be able to get a surprise kill.
0/0 Palkia
50.78 - 60.12 %
Again a SR-less 2HKO. Scarf Palkia is still outspeeded too.
176/176 Scizor
58.15 - 68.62 %
A guaranteed 2HKO all the time. Scizor manages 75.77 - 89.42 % back with U-Turn, meaning you can at least get him to half on his way out, or 34.42 - 38.23 % with Bullet Punch, so you can easily 2HKO if it's Banded into BP.
Hidden Power [Ice] Vs...
6/0 Garchomp
94.97 - 112.85 %
OHKO with SR, 66.67% chance without it. We knew this anyway really, but I figured I should post it. Outspeeds even Scarf sets too remember.
252/0 (CB) Groudon
40.59 - 48.02 %
A 3.55% 2HKO with SR.
112/0 (RP) Groudon
44.44 - 52.57 %
80.08% 2HKO with SR. Even after the RP, Jolteon still outspeeds, so when they try to EQ you after the boost, finish them off.
*You can also switch into the Paradancer to take the TW, but as an OHKO is impossible, you'll have to switch out.*
32/8 Rayquaza
90.25 - 106.96 %
An OHKO with SR, or after one turn of LO. After a DD, even Jolly Rayquaza is still outsped, so unless it uses Extremespeed on you, you win.
Shadow Ball Vs...
6/0 Latios
35.10 - 41.72 %
A 3HKO with or without SR. This is obviously too little, made worse if it's a CM set. Latias is even worse so I won't even post it. As this is not so useful, Sleep Talk is probably the better choice here.
Counters
Dialga has an easy time taking any of these attacks and he is immune to Toxic, so he's the number one problem. Thunder hits hardest, but still only manages 25.88 - 30.46 % (4HKO lol) on the mixed attacker set.
Giratina takes between 28.97 - 34.13 % from Shadow Ball, a 4HKO at best. Toxic would do a job on him, but the number that carry ResTalk negates this.
Lati@s have their way with this set too.
I'm going to continue testing this. I could do with another filler over Shadow Ball it seems, as even on Lati@s it's useless.
C&C would be useful cheers. :)