Floatzel

Revenge Floatzel Zeromous EG

Floatzel @ Life Orb / Muscle Band
Jolly
6 HP / 252 ATK / 252 SPD

-Pursuit
-Aqua Jet
-Brick Break
-Waterfall / Ice Fang

With 115 base Speed Floatzel can outspeed Gengar, Espeon and Froslass and hit them back with a Pursuit as they run (Or even if they stay in as Floatzel has 105 base Attack). Aqua Jet hits speedier, or boosted foes and will get a surprise STABed, SE hit on Aerodactyl and Dugtrio. Brick Break will hit Steels who may wall him otherwise. Waterfall is for a strong secondary STAB, but Ice Fang gives better coverage. His speed rivals Persian, Starmie, Sneasel, Raikou, Ambipom and Azelf, all of which will take great damage from one of this guys moves. Grass Knot only gets 60 base power on him too.

Counters
If any of the things mentioned above are packing a Choice Scarf then Floatzel will go down as he has only 55 base defense, 50 base special defense and 85 base Hp. Anything with a priority move will also surprise Floatzel, as long as he doesn't use Aqua Jet on the same turn. Bulky Waters will resist Aqua Jet, Waterfall and Ice Fang (Unless it's Swampert) so they won't go down very easily. 105 Attack sounds good, but he is only ranked 72nd, so any big defense mon won't feel much pain. Finally, anything packing a STAB Thunderbolt will probably OHKO him.

You could slap a Choice Band on this set easily enough and have the same results if you're willing to sacrifice versatility for power. If you want to abuse Aqua Jet, you could also run an Adamant nature for massive damage.

Perhaps consider Crunch over Pursuit if not using a CB since it'll hit Starmie if she stays in to TBolt you or Slowbro, who walls you otherwise and can kill you with Grass Knot.

For the counters section, basically any physical wall can take him and kill him pretty easily.