Shamelessly stealing this format from Dex, adding my opinions in its place.
Green for High Approval,
Yellow for being on the fence,
Red for Disapproval
Knock Off: One of the most powerful tools a wall can have, it is especially useful because it can heavily annoy a lot of the best switch-ins for our electric attacks. Definitely should be considered for a move slot.
Toxic: Toxic is a good option on walls but im not sure that its the right fit for this Pokémon. Given that some of the best theoretical switch ins (Gliscor, Equilibra, Slowking) are immune to toxic it might not fit as well as some other utility options.
Nuzzle / Glare: Both are pretty strong and good options to threaten a significant portion of attackers that may attempt to switch into us. Can be a tadbit redundant given we might be spamming moves like Discharge but they can still be pretty useful as options.
Defog / Rapid Spin / Court Change: There's definitely an argument for including anti-hazard options, especially since we threaten the Defog Blocker of choice in Ghold.
Haze: Most of our targets either don't setup or have around it to take advantage of us while we haze, don't think we can abuse it well.
Heal Bell: Alright move. We might be able to fit it but it doesn't synergise that well with our toolkit.
Soak: Given how Electromorphosis works I think there's enough of an argument to include this move. Usual switch-ins to this Pokemon can be forced out as the loss of stab to hit this pokémon with + a new weakness to its electric attacks can force them out. Perhaps not as consistent as other options of utility but it is quite nice.
Strength Sap: This move can get pretty annoying pretty fast, the combo of sapping physical attackers as they try to switch in and then potentially living hits then hitting with electromorphosis could prove to be a little too strong. It also means this pokémon's healing won't work in front of Gholdengo, which is one the of the main reasons our typing was chosen.
Will-o-Wisp: Hits a large number of switch-ins and can cripple them into becoming positive matchups. Not too convinced if we should include it but it has a good argument for its inclusion.
50% Recovery: No reason why not to give it this, 35 necesitates ways to circumvent chip damage and recovery is the best way foward. Shame about pp nerfs.
Parabolic Charge: I think we would very much prefer to run normal STAB options since they deal more damage but this move could be admitedly very useful if we take the route of Defensive setup with Calm Mind or another option.
Thunderclap: We want to go on a more defensive route for a wall, have defensively oriented walls ever used Sucker Punch? I doubt it.
Taunt / Encore: Given that we are a wall I dont see us having a case for good speed in order to be using either of this moves.
Super Fang: I think I am a fan of this one. Takes significant chunks of health both from ground types and other offensive pokémon trying to switch in, which is especially good considering many of them lack recovery options. Compliments other options like Knock Off and coverage.
Cotton Guard/Cosmic Power/Amnesia: I can see the argument for them, defensive setup could technically fit this CAP's desire to stay in and tank hits to dish back powerful electric attacks but
U-turn: I would rather find different ways for 35 to find progress, especially given how its ability works, but it is certainly a usable option over Volt Switch.
Roar/Whirlwind/Circle Throw/Dragon Tail: Not a fan of the phazing moves that deal damage, they are inaccurate and don't help much vs the switchins to this pokémon. Roar and Whirlwidn on ther other hand are consistent and can help against threats like Darkrai that electromorphosis may not deal with in one hit.
Heart Swap: Shrimp never uses this move and I don't think it has used it since maybe gen 5, hard pass.
Healing Wish: Paralysing the opponent into a healing wish is the only reason why i think there is an argument for the inclusion of this move. Otherwise we as a wall most likely never going to think of using this move.
Switcheroo / Trick: We don't have an ability to take advantage of this, and one of our targets is Gholdengo, so dedicating a slot to be weaker against it seems bad, not a fan.
Wish: Given how much this pokémon will want to stay in, I don't think it will use this move a lot. The Volt Switch + Wish combination is still interesting however.
Dual Screens: I was gonna bold this red but thinking about it a Electrophorphosis user using screens to tank hits and activate Electromorphosis to scare removers away could in theory be a decent way to abuse the abilty. I can see and argument for this on.
Magnet Rise: One of the biggest reasons that I was against ground inmmunities during the ability stage is that they really don't help that much at beating the ground types of the tier. Gliscor can toxic you, Tusk can use its fighting stab, etc. Staying in on ground type pokémon accomplishes absolutely nothing and gives the opponent time to setup or remove hazards with many of them. Other options do the same without sacrificing a moveslot to a mostly useless move.
Pain Split: I doubt we will be able to use this move, especially since better recovery options exist andn
Chilling Water / Mystical Fire / Lunge: Lunge is a fake move used by fake mons. I kinda like the other two as coverage, especially Chilling Water since I find it to be a less egregious addition than Scald, even if its significantly worse.
Psychic Noise: Not STAB to abuse this on + using other coverage options might be better. Pass.
Skill Swap / Gastro Acid: Only there for Gliscor who can switch out anyways. Very bad choices.
Scald: It is indeed coverage, but im not a fan of it. SV limited scald distribution by a lot so to add a pokémon that truly doesn't need it seems unnessesarry to me, especially when other coverage can do the job as well.
How strong can we allow our Electric type STAB options to be in tandem with Electromorphosis and still achieve our goal of being a more defensive wall?
I don't think we should limit ourselves with our Electric type STAB options, Electromorphosis naturally requires high powered moves to function and being able to hit back as hard as it can will most likely be this pokémon's selling point among other options in the metagame. If it weren't for the fact that it is a legendary signature I would even vote for the inclusion of
Thunder Cage into consideration due to its ability to support utility options like Toxic or Taunt, but unless tls state that they are willing to free the move I don't see the point in discussing it further. The only argument I could see for limiting our electric stab options would be if we were to balance the pokémon around having coverage in the like of Water or Ice moves, but other than that I think we shoudln't limit our electric stab options.