I'll also throw in my responses.
Crawdaunt from my experiences is actually a pretty lethal Pokemon, because its STAB combo has great coverage that is only walled by Ferroseed and Poliwrath; Crawdaunt also hits like a damn nuke because of Adaptability, so it has 160 Power STABs coming off of an insane Attack stat making it a force to be reckoned with. Once it sets up there is almost nothing that can stop it from wrecking shit. I can see Low B looking pretty good because it's pretty good, but needs more support than an A or S-rank threat to bring out full potential (and with Sub you can use Alomomola as setup bait, sweet)
Dusknoir really needs to stay in Mid D. Adding on to what EonX said, I'll give a long description as to why Dusknoir doesn't do well in the current RU metagame. One of Dusknoir's main problems is that while 100 Attack might make Dusknoir look pretty decent at a glance, that stat is actually very deceptive; Dusknoir has a really weak STAB move with 60 Base Power, which is so weak that it can't even OHKO the frail Azelf without any Attack investment (I know Azelf isn't RU, but he's a good example because he's frail and is weak to Ghost), and none of its moves exceed 75 BP either except EQ, so Dusknoir will struggle to deal any damage. While Dusknoir's defenses are really good, it has pitiful HP (at least Dusclops in UU has far greater defenses with like 256 Defenses apiece, so it can actually wall well), so it's prone to getting 2HKO'd and stuff while Dusknoir lacks any reliable recovery outside of Pain Split, which is rather unreliable. Dusknoir is also really slow, so it has to take a lot of damage before doing what it needs to. Misdreavus and Spiritomb are much better defensively; Misdreavus as as much bulk as Dusknoir while having much better special bulk as well, while it can also support its team with Heal Bell and also have a decently powerful Shadow Ball. Spiritomb is also much better because of its lack of weaknesses, and it trades a Bug resistance for an immunity to Psychic moves as well as useful moves in Sucker Punch, Pursuit, and Foul Play. Offensively, Golurk has a much higher Attack and Iron Fist so it hits a lot harder, while Rotom has more Speed and better power. Dusknoir is simply outclassed and should stay in D; really TR teams are the only place for Dusknoir.
As for Butterfree, SV did a good job at explaining its place in RU.
I'm not sure on Rotom, although I love the SubSplit set, works well with Spikes support from Scolipede.
Ninjask is another one I'm not sure about, I haven't used it so...
				
			Crawdaunt from my experiences is actually a pretty lethal Pokemon, because its STAB combo has great coverage that is only walled by Ferroseed and Poliwrath; Crawdaunt also hits like a damn nuke because of Adaptability, so it has 160 Power STABs coming off of an insane Attack stat making it a force to be reckoned with. Once it sets up there is almost nothing that can stop it from wrecking shit. I can see Low B looking pretty good because it's pretty good, but needs more support than an A or S-rank threat to bring out full potential (and with Sub you can use Alomomola as setup bait, sweet)
Dusknoir really needs to stay in Mid D. Adding on to what EonX said, I'll give a long description as to why Dusknoir doesn't do well in the current RU metagame. One of Dusknoir's main problems is that while 100 Attack might make Dusknoir look pretty decent at a glance, that stat is actually very deceptive; Dusknoir has a really weak STAB move with 60 Base Power, which is so weak that it can't even OHKO the frail Azelf without any Attack investment (I know Azelf isn't RU, but he's a good example because he's frail and is weak to Ghost), and none of its moves exceed 75 BP either except EQ, so Dusknoir will struggle to deal any damage. While Dusknoir's defenses are really good, it has pitiful HP (at least Dusclops in UU has far greater defenses with like 256 Defenses apiece, so it can actually wall well), so it's prone to getting 2HKO'd and stuff while Dusknoir lacks any reliable recovery outside of Pain Split, which is rather unreliable. Dusknoir is also really slow, so it has to take a lot of damage before doing what it needs to. Misdreavus and Spiritomb are much better defensively; Misdreavus as as much bulk as Dusknoir while having much better special bulk as well, while it can also support its team with Heal Bell and also have a decently powerful Shadow Ball. Spiritomb is also much better because of its lack of weaknesses, and it trades a Bug resistance for an immunity to Psychic moves as well as useful moves in Sucker Punch, Pursuit, and Foul Play. Offensively, Golurk has a much higher Attack and Iron Fist so it hits a lot harder, while Rotom has more Speed and better power. Dusknoir is simply outclassed and should stay in D; really TR teams are the only place for Dusknoir.
As for Butterfree, SV did a good job at explaining its place in RU.
SilentVerse said:Nah, Butterfree imo is a Pokemon that's solidly C rank. Quiver Dance isn't outclassed at all really; Tinted Lens Bug Buzz gives Butterfree a huge niche over Lilligant, since it means that Butterfree has virtually perfect neutral coverage with just that move, as the only common Pokemon in RU that resist Tinted Lens Bug Buzz is like, Emboar and Moltres This means that Butterfree can actually be more difficult to wall than Lilligant in certain circumstances, as Lilligant will always have a slew of hard counters depending on its Hidden Power, while Butterfree is only walled by Emboar, Moltres, and stuff like Clefable, which Lilligant can have a lot of issues beating as well. While Butterfree is definitely a lot frailer and has a devastating weakness to Stealth Rock, the fact that it can run Substitute in the last slot does help make it harder to revenge kill, and the presence of weak defensive Pokemon like Uxie / Amoonguss / Tangrowth and its access to Sleep Powder gives it some nice set up opportunities. Granted, it does require quite a bit of support to work effectively, but it definitely has a solid niche in RU and can be very strong given the right support, so low / mid C rank is probably the best place for it.
I'm not sure on Rotom, although I love the SubSplit set, works well with Spikes support from Scolipede.
Ninjask is another one I'm not sure about, I haven't used it so...



























