Honestly, I don't really see him doing well in OU at all. The only thing he has going for him is the speed, but that's easily beaten by common scarfers such as Kartana. All I can see him doing is acting as an emergency check to Greninja, and while it looks like the scarf set will rise again, it won't really do much to Zeraora, a Hydro Pump only dealing around 60% of damage, allowing Zeraora to retaliate and secure a kill. As for sets, Zeraora will pretty much need Hidden Power Ice, otherwise it gets countered by scarfed Kartana and hopelessly walled by defensive Lando-T. Here are some sets I can see him running:
Zeraora @ Life Orb
Ability: Volt Absorb
EVs: 252 Atk / 4 SpA / 252 Spe
Naive Nature
- Volt Switch
- Close Combat/Fire Punch
- Plasma Fists
- Hidden Power [Ice]
This set up here, I think will be his most popular one, as it allows him to gain momentum with Volt Switch, and also act as an attacker. However, I can see another goofy set that will probably rise if Zeraora keeps at it in OU:
Zeraora @ Firium Z
Ability: Volt Absorb
EVs: 252 Atk / 4 SpA / 252 Spe
Naive Nature
- Volt Switch
- Fire Punch
- Plasma Fists
- Hidden Power [Ice]
This is a really interesting tech set that exploits Zeraora's inability to break past Ferrothorn and Mega Scizor without Close Combat, which otherwise wall it. However, it does strap off a Z slot that could be used on something otherwise more useful.