Guess it depends if you want to use one as a Toxic Staller/ Baton Passer/ Sweeper. Emonga would function in an in game rain dance team too with Thunder, though there are probably better choices for competitive battling.
Ability: Motor Drive
@ Air Gem or nothing
EV: 252 Speed, 252 HP, 6 Def
- Electro Ball (speed + STAB damage)
- Volt Switch/ U-Turn (quick switch out)
- Acrobatics (x3 with Air Gem, x2 w/o and also STAB)
Role: Toxic staller
@ Light Clay
- Encore/ Roost
- Light Screen
- Baton Pass
That'd be pretty annoying and I think you'd lose a few friends.
Imo, if the rest of your team sets things up, Emonga can be an especially good sweeper, cruising on its high speed stat.