Mega Sceptile actually seems pretty interesting as a Koko counter. Maybe pairing it with something like Gyarados which is quad-weak to Electric to be able to counter it would be good (although I don't really know the VGC meta atm LOL). I'm not entirely sure if Ice types themselves are still a part of the meta other than Pokemon that just use Ice Beam (Cresselia, Tapu Fini), but I dunno.
Here's an example moveset:
Sceptile @ Sceptilite
Ability: Overgrow
EVs: 252 SpA / 4 SpD / 252 Spe
Timid Nature
- Leaf Storm (STAB)
- Dragon Pulse (STAB)
- Protect
- Hidden Power Ice (To deal with Landorus)