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Not really.
252 SpA Mega Sceptile Leaf Storm vs. 0 HP / 0 SpD Mega Manectric: 277-327 (98.5 - 116.3%) -- 87.5% chance to OHKO
Although you're right, if Sceptile bites it, then nothing would handle it. Although Light Screen on Klefki would help a little. I just feel something should be able to boost. Perhaps a CM Lefties Raikou instead?
252 SpA Mega Sceptile Leaf Storm vs. 0 HP / 0 SpD Mega Manectric: 277-327 (98.5 - 116.3%) -- 87.5% chance to OHKO
Although you're right, if Sceptile bites it, then nothing would handle it. Although Light Screen on Klefki would help a little. I just feel something should be able to boost. Perhaps a CM Lefties Raikou instead?