After doing some tutoring since this was first written, her current moveset as of the writing of this comment is Night Slash/Air Cutter/Heat Wave/Superpower @ Scope Lens, because I agree with you on a crit build even without Super Luck.
We have some mon that have... unfortunate genetics working against them (Kracko and Atreyu both clearly specialize in one side of the physical/special split yet have a nature that nerfs theirs, for example) but nothing that's proven completely insurmountable at least in PvE. Sure, Nimbly would be better on a crit build with Super Luck just like Atreyu would be better if he were +Atk/-SpA instead of literally the other way around, but what they have still works.
Which is all my way of saying just ignoring her Insomnia and giving her a crit build anyway should still be fine. And you're right; that even gives her more of a unique niche instead of ending up somehwere around "the Gmork we have at home" territory.
Of those four moves, all of them seem fairly solid for what she is and what she's going for here, except maybe Heat Wave. That one is fine, actually, but running it maybe gets her a bit close to Gmork's "Dark type who also burninates things" lane without even addressing that many of her actual weakness types. Like, that handles Ice and maybe Bug (which is actually neutral but I'm counting it as a weakness because Bugsy's Scyther hits like a damn truck unless you specifically resist.) Meanwhile, Superpower covers Ice and Rock while it's at it. Alas, we have no options to address her Electric weakness unless you count her Hidden Power, which is Ground type and... about as powerful as Air Cutter without the STAB. Maybe, honestly, but it feels hard to justify when something like Heat Wave has almost twice the base power.
Maybe just get her Psychic for that slot to at least neutral Electric, beat Fighting, and because it's fucking Psychic. I would say the catch is that TM29 is such a pain in the ass to get more of, but being one of the 10K Game Corner prizes, it's actually such bullshit that it wraps back around into "you know what, nah, I'm allowing myself to just hack an extra one in at that point" range next to the Battle Frontier prizes.
Or, you know, maybe Sucker Punch is good after all, since her speed is... not great and thus she could use a priority move, even if it involves some gimmicky predicting for it to not fail.
This is all my way of dodging around the fact that you already suggested Substitute here, but I feel like that'd be better suited to someone who's faster. It seems like something of a waste to get pelted before even getting to set it up, you know?
The main problem with this or really any build is that what sets her apart from Gmork, and what could even bump her back to the Tier 1 mons if it weren't so underwhelming, is that she's currently our only Flying STAB. While we have one other half-Flying type, it's Falkor and she chose not to acknowledge that part of her heritage at all for the same reason Nimbly is currently struggling with it: Gosh the Gen IV Flying move pool sucks unless you're lucky enough to know Brave Bird or hop in the sack with someone who does.
no subject
We have some mon that have... unfortunate genetics working against them (Kracko and Atreyu both clearly specialize in one side of the physical/special split yet have a nature that nerfs theirs, for example) but nothing that's proven completely insurmountable at least in PvE. Sure, Nimbly would be better on a crit build with Super Luck just like Atreyu would be better if he were +Atk/-SpA instead of literally the other way around, but what they have still works.
Which is all my way of saying just ignoring her Insomnia and giving her a crit build anyway should still be fine. And you're right; that even gives her more of a unique niche instead of ending up somehwere around "the Gmork we have at home" territory.
Of those four moves, all of them seem fairly solid for what she is and what she's going for here, except maybe Heat Wave. That one is fine, actually, but running it maybe gets her a bit close to Gmork's "Dark type who also burninates things" lane without even addressing that many of her actual weakness types. Like, that handles Ice and maybe Bug (which is actually neutral but I'm counting it as a weakness because Bugsy's Scyther hits like a damn truck unless you specifically resist.) Meanwhile, Superpower covers Ice and Rock while it's at it. Alas, we have no options to address her Electric weakness unless you count her Hidden Power, which is Ground type and... about as powerful as Air Cutter without the STAB. Maybe, honestly, but it feels hard to justify when something like Heat Wave has almost twice the base power.
Maybe just get her Psychic for that slot to at least neutral Electric, beat Fighting, and because it's fucking Psychic. I would say the catch is that TM29 is such a pain in the ass to get more of, but being one of the 10K Game Corner prizes, it's actually such bullshit that it wraps back around into "you know what, nah, I'm allowing myself to just hack an extra one in at that point" range next to the Battle Frontier prizes.
Or, you know, maybe Sucker Punch is good after all, since her speed is... not great and thus she could use a priority move, even if it involves some gimmicky predicting for it to not fail.
This is all my way of dodging around the fact that you already suggested Substitute here, but I feel like that'd be better suited to someone who's faster. It seems like something of a waste to get pelted before even getting to set it up, you know?
The main problem with this or really any build is that what sets her apart from Gmork, and what could even bump her back to the Tier 1 mons if it weren't so underwhelming, is that she's currently our only Flying STAB. While we have one other half-Flying type, it's Falkor and she chose not to acknowledge that part of her heritage at all for the same reason Nimbly is currently struggling with it: Gosh the Gen IV Flying move pool sucks unless you're lucky enough to know Brave Bird or hop in the sack with someone who does.