Jab: Pretty much his default jab, but maybe with claws instead? He should probably keep the Silver Bow in his moveset somehow, considering he does use it in Uprising
Ftilt: A three-hit combo move similar to Bayo's jab 1, 2, 3 (not the rapid jab tho) with claws
Dtilt: Dtilt could probably stay the same, an alternate idea could be something like Kamui's dtilt with claws (I'm seeing him use claws infused with a firey energy, so they'd have a trail like Kamui's too)
Utilt: Takes his bow and spins it (like his uair) first at a slight upward angle in front of him, then directly above him, then at a slight upward angle behind him (like the first strike, but behind him). High risk, high reward move. Takes a little while to finish and has minimal shieldstun, but if connected does a lot of damage and sets up for combos (especially into bair). Covers a wide area like DK's utilt.
DA: He could have a DA similar to this guys spinning attack in Dragon Quest 9
(For those of you who didn't play that amazing game, he spins like a drill headfirst, a little similar to Kamui's DA)
Fsmash: The three-hit jab-esque combo done with Arms in Uprising, performed with the Electroshock Arm. Similar to Cloud's fsmash in properties. All Arm-based attacks use the Electroshock Arm and make the sound the Electroshock Arm does on hit in Uprising.
Usmash: A Shoryuken-esque upward strike like Knuckles' usmash or Mario's utilt with the Electroshock Arm.
Dsmash: Okay, this one is pretty hard to describe. He first thrusts the Electroshock Arm forward at a low angle like Mac's dtilt, or the first hit of Cloud's dsmash. This knocks them behind him at a diagonal angle, and Dark Pit turns to hit them again with the Arm. He holds the Arm at the same angle that he holds the Staff in this picture:
The two hits link like Cloud or Tink's dsmash, but it kills diagonally.
Nair: A spin with claws similar to Lyn's nair
Fair: Similar to Cloud or Mario's fair, he smashes in a downward arc with the Arm. The animation looks more like Cloud's fair, but he does a roll afterward like Mario's fair. FH autocancels, but has low landing lag anyways. Spikes on the lower part of the swing like Cloud's.
Bair: A quick strike backwards with the Arm, very similar to Lyn's bair. Low landing lag and can space well.
Dair: A downwards strike like Marth's dair, with a spin on the end (like after an aerial side b with Pit, but only one spin) replacing the slow animation Marth has during aerial end lag.
Uair: Just his normal uair, but it does a single hit like in PM, making it better for juggling, but it can't drag opponents around like Pit's.
Neutral B: Fires the Dark Pit Staff. The projectile is small (it looks a lot like Bayo's charged Bullet Climax projectile) but has infinite range and gets stronger the farther it travels, to the point that it can OHKO in edgegaurd situations. It charges automatically, but it's rather slow for a charge (something like 15 or 20 seconds). If used uncharged, it's comparable to Fox's lasers.
Side B: A combo attack with claws and bow like Cross Slash or Dancing Blade. It can be angled like Marth's side b, but only has two strikes. First strikes use claws and seconds strikes use the bow.
Down B: Jetstream Orbitars fly around him, deflecting projectiles and creating a powerful windbox.
Up B: Power of Flight
Final Smash: Similar to Snake's Final Smash, Dark Pit flies into the foreground, creating an Uprising air battle-esque interface with Dark Pit's wings glowing with power. A fires the Staff, you move by moving, and you get ten shots or 30 seconds before the FS ends (unlike in Uprising the shots don't have to charge - you get full-charged shots every time).
Pummel: Faster than Pit's but deals less damage
Fthrow: A powerful gut punch from the Electroshock Arm sends them flying. A kill throw with high knockback scaling, but low base knockback. Kills around 150 from center stage. Has a lot of endlag, making it impossible to combo with.
Bthrow: Puts the opponent behind him and stabs them through with a claw, like Shulk's bthrow. Doesn't do a lot of damage, but can combo into DA or nuetral b at lower percents.
Uthrow: Throws them up and shoots them with the Dark Pit Staff, like Lyn's uthrow. The shot cannot be avoided by DI and the throw+the shot kills around 180.
Dthrow: Throws them down and slashes them with claws in a similar animation to Lyn's dthrow. Has an angle like Mario's dthrow at mid percents, allowing it to combo into fair spike at low percents. Not very useful after 40-ish percent however.