>>34738232most likely BL or OU.
koko will still be run more due to electric terrain memes giving it overall better synergy with rain and hawlucha, but zera's higher speed and better use of offensive stats means it can shut down ash-greninja or lopunny. also, being the fastest scarfer in the tier is...nice, I guess, for potentially beating a +1 zygarde and killing off weakened lando. access to close combat allows it to pick off ttar and heatran too, so there's something.
but yeah, overall it just doesn't mesh well into the current meta. it's way way way too fucking strong to drop to UU, though.