As of Gen 9
-Partner Pikachu: Zippy Zap, Spilshy Splash, Pika Popow, Floaty Fall
-Partner Eevee: Baddy Bad, Bouncy Bubble, Buzzy Buzz, Freezy Frost, Glitzy Glow, Sappy Seed, Sizzly Slide, Sparkly Swirl, VeeVee Volley
-Alolan Marowak: Boomerang, Shadow Bone
-Porygon, Porygon2, Porygon Z: Conversion, Conversion2 (from during gen1-4 Porygon would also have Sharpen which it would share with porygon2)
-Galarian Slowking: Eerie Spell, Chilly Reception
-Vespiquin: Attack Order, Defend Order(during Gen4-7 it would have Heal order as well)
-Cresselia: Lunar Dance, Lunar Blessing
-Manaphy: Take heart, Heart Swap
-Victini: V Create, Searing Shot
-Reshiram: Fusion Flare, Blue Flare
-Zekrom: Fusion Bolt, Bolt Strike
-Kyurem White: Ice Burn, Fusion Flare
-Kyurem Black: Fusion Bolt, Freeze Shock
-Zygarde all forms: Thousand Arrows, Lands Wrath, Core Enforcer, Thousand Waves
-Kommo-o: Clanging Scales, Clangorous Soul
-Necrozma, all forms: Photon Geyser, Prismatic Laser. Dusk Mane: Sunsteel Strike, Photon Geyser, Prismatic Laser. Dawn Wings: Moongeist Beam, Photon Geyser, Prismatic Laser
-Cinderace: Court Change, Pyro Ball
-Morgrem, Grimsnarl: Confide, False Surrender (during Gen 8, Grimsnarl would have Spirit Break instead of confide)
-Hydrapple: Fickle Beam, Syrup Bomb
-Raging Bolt: Thunderclap, Rising Voltage
Before Gen 9
These are all Pokemon that have had multiple Signature moves in previous generations and do not have any signature moves as of the current generation
Rattata, Raticate: Gen 1-3: Super Fang, Hyper Fang
Cubone, Marowak: Gen 1-7: Bone Club, Boomerang
Hitmonlee: Gen 1-2. Gen 1: High Jump Kick, Rolling Kick, Jump Kick. Gen 2: Mega Kick, Mach Punch, Jump Kick, High Jump ick.
Hitmonchan: Gen 2: Mach punch, High Jump Kick
Tyrogue: Gen 2: Mach Punch, High jump kick
Hitmontop: Gen 2: Mach Punch, High Jump Kick, Triple Kick
Klink, Klang, Klinklang: Gen 5-6: Shift Gear, Gear Grind
Keldeo: Gen 5: Sacred Sword, Secret Sword
Klefki: Gen 6: Fairy Lock, Crafty Shield
Eternatus: Gen 8: Dynamax Cannon, Eternabeam
Source: https://bulbapedia.bulbagarden.net/wiki/Signature_move
