Add Energy Ball, Shadow Ball, Nasty Plot, and Hidden Power Fighting to Decidueye:
It's special attack is only 7 lower; I think a special set is possible to make variety.
To add to what
A Cake Wearing A Hat said, keep in mind that some Pokémon already have mixed sets and can learn both nasty plot and swords dance, namely Lucario and Infernape. These two are a tier above Decidueye in terms of speed, have access to priority moves, and do not have a signature move as useful as Spirit Shackle (and potentially Sinister Arrow Raid), which is physical. I think it's better to keep Decidueye as is.
Add Swords Dance and Will-O-Wisp to Incineroar:
Intimidate helps it force switches. These moves could help it take advantage of that opportunity.
Dunno about that. IIRC it only has assault vest, choice band and choice scarf as possible items, and I like those. Particularly AV, because it allows it to tank both physical and special attackers (bare strong SE moves). Maybe WoW + leftovers could be an option, but I'd keep SD out.
Add Ice Beam and Energy Ball to Primarina:
More coverage options never hurts, plus it means it's not running the same set every time. (well mostly)
When looking for coverage moves, you generally want to achieve perfect neutral coverage, especially against threats. Energy Ball does nothing in that regard that its stab moves don't, except against Gastrodon and water absorb Seismitoad. In practically any other situation, its other moves will do at least what energy ball would do.
Add Brave Bird and Return to Toucannon:
In the case of Brave Bird, it's because I'm sure people won't like relying on a negative priority move to kill slower mons. Return is just strong in general thanks to getting STAB.
I think those are good ideas, but I'd want to keep Beak Blast because of how usefull it can be. If you can't afford a switch out against a physical attacker that will kill Toucannon, getting the burn opportunity is massive.
Add Ice Punch and Thunder Punch to Gumshoos:
More coverage can always be counted on when the Pokemon you get are random.
Nothing to add to what
A Cake Wearing A Hat said.
Add Drain Punch, Thunder Punch, and Crabhammer (you can say no on this one if you want) to Crabominable:
More options is great for a Pokemon who's lacking in them. (It only has four moves right now) and Drain Punch could be interesting when it gets an Iron Fist Boost (still lower than Close Combat's 120, but an option)
Same.
Add Hidden Power Ground and Calm Mind to Oricorio (all forms):
All of the analysis's suggest Calm Mind on all of them, and HP Ground can put work into some targets for a Pokemon lacking options anyway.
I like this idea. Having access to roost also provide reliable recovery that allows Oricorio to set up multiple times.
Add Sticky Web to Ribombee:
It's the fastest thing to learn it, which is definitely useful.
I've already explained my position on that earlier in this thread. Not all convinced, but then, Masquerain does get sticky web and QD, so dunno.
Add Sucker Punch to Lycanroc (all forms):
This move is also shown on the normal and dusk analysis's, and midnight would benefit from another priority option.
Midnight already gets it. Midday is super fast and besides Deoxys (which gets kaboomed by a boosted accelrock anyways), I'm not sure it would have that much use because it just isn't that much stronger than accelrock on neutral hits. Dusk is a tad slower and tough claws boosts sucker punch, which would make it more viable against fast threats. So I'd be down to adding it to Dusk.
Add U-Turn to Wishiwashi:
Needs more options.
Suggested that the other day. YES PLEASE.
Add Knock Off and Toxic to Toxapex:
Again, More options for something with only 5 moves.
I think it does its job pretty well as is.
Add Toxic, Rest, and Sleep Talk to Mudsdale:
Toxic is another option yet again, and RestTalk can synergize with Stamina depending on the situation.
Now that's something I'd really want to see.
Add Magic Coat to Araquanid:
A few analysis's mention this move, which could bring help to variety.
Don't think that would be useful in randbats.
Add Giga Drain to Shiinotic:
Having the other STAB option never hurts, especially when it can heal HP back.
Yes please.
Add Toxic, Substitute, and Hidden Power Grass to Salazzle:
Making use of Corrosion could be an interesting idea to experement with, and HP Grass gives another coverage option for NP sets.
It's so weak it won't be able to stall much. Keep it as a glass cannon.
Add Drain Punch and Earthquake to Bewear:
Drain Punch has use over Hammer Arm for being able to recover HP.
Drain Punch would be nice. EQ doesn't really add much IMO, except the possibility of hitting fire types harder (but it would still miss the KO in a lot of cases).
Add Giga Drain and Hidden Power Ground (or Fire) to Comfey:
Having priority Giga Drain alongside Draining Kiss can be interesting for certain teams to handle.
Giga Drain and Draining Kiss face a lot of the same resists (fire, steel, poison), but Giga does allow to hit water, rock and/or ground types pretty hard. I think this could use some experiment, but overall, I'm not sure it'd be that useful. Comfey being mostly a utility 'mon, no need for HP.
Add Block and Spite to Pyukumuku:
It uses Block in a lot of formats, and Spite works well with it.
Block
could be nice. I'd keep Spite out of randbats, however.
Add Swords Dance to Type: Null:
It too uses it in real formats.
Nothing to add to what
A Cake Wearing A Hat said.
Add Hyper Voice and Shadow Ball to Silvally (Normal) and Defog to most forms (pick the ones which don't get it):
Hyper Voice can mean Special sets are a possibility, and has good coverage combined with Shadow Ball. Defog is a usefull move in general.
Nothing to add to what
A Cake Wearing A Hat said. Defod being a possibility for most forms should be a must though.
Add Signal Beam to Silvally (Bug): (Hesitant on this one)
While Signal Beam can make an ok STAB, I'm not sure if clicking STAB is what you want to do with it.
Swap Multi-Attack for Thunderbolt on Silvally (Electric):
All of it's other moves are special; it gains the ability to use an atk lowering nature from it.
Swap Multi-Attack for Flamethrower on Silvally (Fire):
Read above.
Swap Multi-Attack for Shadow Ball on Silvally (Ghost):
Again, read above.
Swap Multi-Attack for Grass Pledge on Silvally (Grass):
And again.
Swap Multi-Attack for Ice Beam on Silvally (Ice):
And again..
Swap Multi-Attack for Surf on Silvally (Water):
And once more.
Nothing to add to what
A Cake Wearing A Hat said.
Add Shadow Claw to Dhelmise:
It literately has no Ghost STAB listed in it's current move set.
Nothing to add to what
A Cake Wearing A Hat said.
Add Ice Punch, Focus Blast, Flamethrower, Flash Cannon, Stealth Rock, Taunt, and Swords Dance to Kommo-o:
All of these have some kind of use, and it's lacking in options currently.
This adds a lot of options and would make sets all over the place. Better to keep it like it is. Maybe Flash Cannon could be useful for Diancie and Carbink, but that'd be about it.
Add Roost, Toxic, Bulk Up to Buzzwole:
Recovery helps on something with a spread like that. Toxic and Bulk Up can increase options other than just attacking.
Yes please. It's a physically bulky mon and I think this would work.
Add Drill Run and Throat Chop to Pheromosa:
Adds more coverage options.
I don't think it needs those. Drill Run would be mostly for poison types I guess, since a SE drill run doesn't do more than a neutral HJK.
Add Tail Glow and Hypnosis (Debatable) to Xurkitree:
More options other than just attacking.
I hate hypnosis, and while I know some people love the z-hypnosis set, I'd hate its reliability in randbats.
Add Defog to Kartana:
Also another option.
I'd rather keep it full glass cannon.
Add Dark Pulse, Sludge Wave, and Outrage to Guzzlord:
It can run a full special, or a full physical set with these additions.
I don't know if I was dreaming, but the other day I had a celesteela with a leech seed set that had its defense as its higher stat, and no special move. So that means EVs/IVs that are not speed could also be adjusted for certain Pokemon - if that wasn't a dream, obviously. If that is possible, I think it would be a good idea. If you have a full physical set (knock off, outrage, hammer, EQ...), keep it as is, but if it lands only special attacks (dark pulse, sludge wave, draco meteor/dragon pulse and fire blast), lower its attack EV to have special attack as its highest stats. But I feel like that becomes too many moves on its moveset.