Spoiler-Free: All (notable) Movepool additions in the Mega Dimensions DLC

[TheDragonTexasWarrior2001]

DISCLAIMER Some of these movepool additions may not transfer over to Pokémon Champions nor Gen 10 (remember Ice Beam Gardevoir or Mach Punch Lucario?)

Special thanks to RoiDadadou, Kap, and crew

Raichu - Drain Punch, Dazzling Gleam
Alolan Raichu - Dazzling Gleam
Wigglytuff - Moonblast, Fake Out
Persian - Spikes
Alolan Persian - Spikes, Toxic Spikes
Starmie - Triple Axel, Charge Beam
Dragonite - Vacuum Wave

Ariados - First Impression
Crobat - Knock Off, Psychic Fangs
Porygon2 (and Porygon-Z) - Volt Switch

Medicham - Blaze Kick
Zangoose - Fake Out
Seviper - Scale Shot
Milotic - Calm Mind, Dazzling Gleam
Kecleon - Shed Tail, First Impression, Scale Shot, Power Whip
Banette - Icicle Spear
Chimecho - Boomburst (as we all know)
Salamence - Scale Shot

Staraptor - Bulk Up, Knock Off, and Blaze Kick
Roserade - Mortal Spin
Garchomp - Nasty Plot, Vacuum Wave
Abomasnow - Ice Hammer
Rotom - Parabolic Charge, Taunt, Parting Shot
Darkrai - Vacuum Wave

Liepard - Parting Shot
Simisage, Simisear, and Simipour all get Fake Out
Simisage - Drain Punch
Simisear - Scorching Sands
Sawk - Swords Dance, Mach Punch, Blaze Kick
Scolipede - First Impression and Mortal Spin
Cofagrigus - Psyshock, Thunder Wave, Parting Shot, Stealth Rock, Icy Wind
Amoonguss - Toxic Spikes, Dazzling Gleam, First Impression
Eelektross - Psychic Fangs and Muddy Water
Galarian Stunfisk - Toxic
Golurk - Fissure (nothing keeping that)
Terrakion - Head Smash
Virzion - Horn Leech and Stealth Rocks
Keldeo - Earth Power, Ice Beam, Stealth Rock, Reflect, and Light Screen
Meloetta - Flip Turn

Greninja - Vacuum Wave
Diggersby - Drain Punch
Meowstic (both genders) - Moonblast, Teleport
Malamar - Octolock
Heliolisk - Shed Tail
Dedenne - Fake Out
Hoopa - Psychic Fangs

Crabominable - Mach Punch, First Impression, Taunt
Golisopod - U-Turn
Palossand - Nasty Plot, Fake Out
Magearna - Vacuum Wave, Power Gem

Corviknight - Heavy Slam
Toxtricity - Parabolic Charge
Grapploct - Bullet Punch, Mach Punch, Knock Off
Sirfetch’d - U-Turn
Me. Rime - Stealth Rocks and First Impression
Runerigus - Knock Off, Parting Shot, Thunder Wave
Falinks - Fake Out
Indeedee (M) - Moonblast, Heat Wave, Moonlight, Wish, Vacuum Wave
Indeedee (F) - Moonblast, Moonlight, Wish
Overqwil - Mortal Spin, Thunder Wave

Flamigo - Triple Axel, Knock Off
Ceruledge - Stone Edge
Grafaiai - First Impression, Toxic Spikes, Reflect, Light Screen
Scovilliain - Nasty Plot, Flare Blitz
Tinkaton - Bulk Up, Heavy Slam, Wood Hammer, Power-Up Punch
Mabosstiff - Knock Off
Tatsugiri - Ice Beam, Flip Turn, Calm Mind
Annihilape - Knock Off
Baxcalibur - Ice Hammer, Psychic Fangs
Gholdengo - Surf

 

[SadisticMystic]

Golurk - Fissure
https://gist.github.com/SciresM/29577c5a59a3be14377484e13cbd9557

 

[KeenSaysGM]

Golisopod got U-turn which is new for it as well

(nvrmnd, didnt see in OP somehow)

 

[AmbientDinosaur]

Magnet Bomb
Cooldown: 8
Power: 95
The user attacks by launching steel bombs that stick to targets.

Damn, they really brought back Magnet Bomb with a vengeance. Galarian Stunfisk has an ususble physical Steel move now!

 

[Avira]

Female Meowstic learns Earth Power now, so not even something like Heatran is safe.

 

[Karxrida]

Keldeo - Earth Power, Ice Beam, Stealth Rock, Reflect, and Light Screen

Holy shit they finally gave Ice Beam to Keldeo? Only took them over a decade.

 

[Metrona]

Grapploct - Bullet Punch, Mach Punch, Knock Off

It also got storm throw, which, under technician, hit harder than CC