So the
SV move dump sheet has been updated for 3.0.0, and now we can see what's going on in the Metronome flag.
New Moves
Every new move is callable via Metronome, except Tera Starstorm. Game Freak has been really generous with the DLC moves lately, and I have to wonder the reason for it considering a certain new move that no one would ever expect to be callable.
Electro Shot: 130 BP special Electric charge move that boosts SpA like Meteor Beam and attacks instantly in rain. This will be a huge hitting move, and even Choice users can still get the stat buff.
Fickle Beam: 80 BP special Dragon move with a 30% chance to double its power naturally. The flavour makes this effect seem mon-specific but I imagine it can still proc regardless.
Burning Bulwark: King's Shield but burns on contact... wait, a Protect clone is callable via Metronome? I did not expect to see this since every other Protect move is purposely not callable by most calling moves, including Silk Trap introduced this gen, but it's a potential bonus for faster mons to block damaging attacks.
Thunderclap: A Sucker Punch clone? In Metronome Battle? Well, at least it has some use against multi-turn moves, but otherwise it's a useless roll since everything is clicking a status move.
Mighty Cleave: 95 BP physical Rock move, with 100% accuracy because that's notable for a Rock move. It bypasses protection, which before today I would say is a useless effect, but they just added Burning Bulwark into the pool, so that's something. Also it makes contact.
Tachyon Cutter: 50 BP special Steel move with perfect accuracy that hits twice. I feel like this is honestly one of the better Steel attacks you could roll which isn't saying much.
Hard Press: A physical Steel-type Wring Out/Crush Grip clone (does more damage when the opponent is at high HP). These moves usually feel pretty useless, but I guess opening the battle with a big hit (120 BP if the same formula) might be appreciated. Also it makes contact.
Dragon Cheer: This is an interesting idea for a support move. It boosts your ally's critical hit ratio by 1 stage, but if they are a Dragon type then they get +2 instead. They can't stack this effect with Focus Energy either way. Not too impactful but I like crits.
Alluring Voice: 80 BP special Fairy move that confuses a target if they boosted a stat this turn, like Burning Jealousy. More fairy options are nice.
Supercell Slam: 100 BP, 95% accurate, physical Electric move that works like Hi Jump Kick where you take crash damage if you miss or hit an immunity (Ground). This probably won't be as bad as HJK since it doesn't ruin your game against ghosts, but it's another really strong move for physicals to use.
Psychic Noise: 75 BP special Psychic move that inflicts the effect formerly known as Heal Block for 2 turns, blocking all healing. This is probably not too impactful without any guaranteed healing sources, but it's not a bad side effect when on an attacking move.
Upper Hand: It's an even more specific version of Sucker Punch that only works against someone using an increased priority move. You would need to somehow call the move with a Prankster mon and use it against another Prankster mon that you're faster than or something, or like a mon with Gale Wings using Sky Attack, which should tell you how convoluted it has to be for this move to work.
Malignant Chain: 100BP special Poison move. This has the same Inflict flags as Poison Fang, so I believe it's a 50% chance to badly poison.
EDIT: Somehow I skipped a move.
Temper Flare: 75BP physical Fire Stomping Tantrum clone. It's alright for a potential 150BP move with all the possibilities to fail.
Old Moves
A lot of legendaries returned and brought their sigs with them too, so there will be a lot of high power action back in the mix, but also a few smaller signature moves too. Porygon brings Conversion and Conversion 2 back, so now you can change your type to Normal or something completely different, as long as you don't Tera. Triple Kick is kind of weak, but Aeroblast and Sacred Fire are some of the high power moves I'm talking about that might add a bit more pressure onto Heracross.
Luster Purge and Mist Ball return, and they've also been uniquely buffed from 70 to 95 power, which adds a lot more STAB for psychics on top of Psycho Boost returning. Over in Gen 4, Rock Wrecker is coming back which a lot of physical mons are probably looking forward to, but not so much Crush Grip.
Gen 5 really leads the charge with legendary sigs with Glaciate, Bolt Strike, Blue Flare, Fusion Flare, and Fusion Bolt all returning as huge elemental attacks. Will we ever see the moment of using both fusion moves in one turn? Gen 6 only has but one returning move but it's a major one in Topsy-Turvy, potentially changing the game for any bulky statbooster. Gen 7 features Sparkling Aria, Floral Healing, Dragon Hammer, and Prismatic Laser, since the other Gen 7 legendary moves have still been uncallable since they changed in Gen 8 for whatever reason. Along with Floral Healing, Decorate is also coming back for anyone who enjoys seeing the chaos of mons causing their own downfall.
I think it's going to be interesting seeing some of these old moves back for the first time in a while, and for me Topsy Turvy is probably the most unique effect of them all that can make or break a game. It's a nice side effect of gamefreak having to readd all the legendaries that the Metronome meta still gets to enjoy a return of their moves.