Pokémon GO is certainly a great game, and one that has certainly nodded to the other aspects of the Pokémon franchise (for example, the Eeveelution name trick corresponding to characters from the anime). But there are other aspects that Pokémon GO has certainly failed in honoring (for example, the horridly-low max CP values of Registeel and Dusclops). Signature moves, moves that are exclusive to one species or evolutionary chain of Pokémon, are also not honored. So why has Niantic not implemented something so simple?
The only two signature moves currently in the game are Transform (exclusive to Ditto) and Bone Club (exclusive to Marowak). But, by looking at the list below the article, you can clearly see there are quite a few more. Some moves (like Miltank's Milk Drink and Palossand's Shore Up) are not damage-dealing moves in the main series, so it makes sense why they are not in Pokémon GO with our current battle system. But others (like Mewtwo's Psystrike and Heatmor's Fire Lash) do deal damage like Thunderbolt, Vine Whip, and Hidden Power do. It makes no sense why Niantic hasn't added some of these moves already, especially to give some Legendaries and forgotten Pokémon something special.
On top of that, many moves are formerly-exclusive to certain Pokémon. For example, Victreebel now has access to Leaf Blade (a move that used to be exclusive to Sceptile). Blast Burn used to be Charizard's exclusive move, Frenzy Plant for Venusaur, Sacred Fire for Ho-Oh, Skull Bash for Blastoise, Muddy Water for Swampert, etc. There are just so many moves, ones that would bring much relevance to many eclipsed and overshadowed Pokémon.
Imagine, Raichu and Octillery could become more relevant in the meta-game with Volt Tackle and Octazooka. Secondary effects to moves could also be added. A Decidueye using Spirit Shackle could keep the opponent from switching their Pokémon when both PVP and Generation 7 are introduced. Niantic adding exclusive moves and secondary effects to moves (like paralysis or burn) would really add a new flavor of depth to the Pokémon GO meta-game.
Make sure to take a look at a list from Bulbapedia below, Trainers! Good luck with your Legendary Beast Raids!
The only two signature moves currently in the game are Transform (exclusive to Ditto) and Bone Club (exclusive to Marowak). But, by looking at the list below the article, you can clearly see there are quite a few more. Some moves (like Miltank's Milk Drink and Palossand's Shore Up) are not damage-dealing moves in the main series, so it makes sense why they are not in Pokémon GO with our current battle system. But others (like Mewtwo's Psystrike and Heatmor's Fire Lash) do deal damage like Thunderbolt, Vine Whip, and Hidden Power do. It makes no sense why Niantic hasn't added some of these moves already, especially to give some Legendaries and forgotten Pokémon something special.
On top of that, many moves are formerly-exclusive to certain Pokémon. For example, Victreebel now has access to Leaf Blade (a move that used to be exclusive to Sceptile). Blast Burn used to be Charizard's exclusive move, Frenzy Plant for Venusaur, Sacred Fire for Ho-Oh, Skull Bash for Blastoise, Muddy Water for Swampert, etc. There are just so many moves, ones that would bring much relevance to many eclipsed and overshadowed Pokémon.
Imagine, Raichu and Octillery could become more relevant in the meta-game with Volt Tackle and Octazooka. Secondary effects to moves could also be added. A Decidueye using Spirit Shackle could keep the opponent from switching their Pokémon when both PVP and Generation 7 are introduced. Niantic adding exclusive moves and secondary effects to moves (like paralysis or burn) would really add a new flavor of depth to the Pokémon GO meta-game.
Make sure to take a look at a list from Bulbapedia below, Trainers! Good luck with your Legendary Beast Raids!
PICHU, PIKACHU & RAICHU: Volt Tackle
PIKACHU: Catastropika (Z-Move)
ASH-HAT PIKACHU: 10,000,000 Volt Thunderbolt (Z-Move)
ALOLAN RAICHU: Stoked Sparksurfer (Z-Move)
MEOWTH & PERSIAN: Pay Day
KADABRA & ALAKAZAM: Kinesis
MACHAMP: Strength
EXEGGUTOR: Barrage
ALOLAN EXEGGUTOR: Dragon Hammer
MAROWAK: Bone Club, Bonemerang
ALOLAN MAROWAK: Shadow Bone
CHANSEY: Soft-Boiled
JYNX: Lovely Kiss
EEVEE: Extreme Evoboost (Z-Move)
PORYGON FAMILY: Conversion, Conversion2
SNORLAX: Pulverizing Pancake (Z-Move)
MEWTWO: Psystrike
MEW: Genesis Supernova (Z-Move)
SPINARAK & ARIADOS: Toxic Thread
OCTILLERY: Octazooka
DELIBIRD: Present
SMEARGLE: Sketch
MILTANK: Milk Drink
LUGIA: Aeroblast
HARIYAMA: Smelling Salts
LATIAS: Mist Ball
LATIOS: Luster Purge
KYOGRE: Origin Pulse
GROUDON: Precipice Blades
RAYQUAZA: Dragon Ascent
JIRACHI: Doom Desire
DEOXYS: Psycho Boost
VESPIQUEN: Attack Order, Defend Order, Heal Order
CHATOT: Chatter
DIALGA: Roar of Time
PALKIA: Spacial Rend
HEATRAN: Magma Storm
REGIGIGAS: Crush Grip
GIRATINA: Shadow Force
CRESSELIA: Lunar Dance
DARKRAI: Dark Void
SHAYMIN: Seed Flare
ARCEUS: Judgement
VICTINI: Searing Shot, V-create
EMBOAR: Heat Crash
AUDINO: Secret Power
KROOKODILE: Power Trip
CINCCINO: Tail Slap
GALVANTULA: Electroweb
KLINKLANG: Gear Grind
BOUFFALANT: Head Charge
HEATMOR: Fire Lash
VOLCARONA: Fiery Dance
RESHIRAM: Fusion Flare, Blue Flare
ZEKROM: Fusion Bolt, Bolt Strike
KYUREM: Glaciate
WHITE KYUREM: Ice Burn
BLACK KYUREM: Freeze Shock
KELDEO: Secret Sword
MELOETTA: Relic Song
GENESECT: Techno Blast
CHESNAUGHT: Spiky Shield
DELPHOX: Mystical Fire
GRENINJA: Water Shuriken
VIVILLON: Powder
AEGISLASH: King's Shield
INKAY & MALAMAR: Topsy-Turvy
HELIOLISK: Electrify
HAWLUCHA: Fltying Press
KLEFKI: Fairy Lock
TREVENANT: Forest's Curse
GOURGEIST: Trick-or-Treat
XERNEAS: Geomancy
YVELTAL: Oblivion Wing
ZYGARDE: Land's Wrath, Thousand Arrows, Thousand Waves, Core Enforcer
DIANCIE: Diamond Storm
HOOPA: Hyperspace Hole, Hyperspace Fury
VOLCANION: Steam Eruption
DECIDUEYE: Spirit Shackle, Sinister Arrow Raid (Z-Move)
INCINEROAR: Darkest Lariat, Throat Chop, Malicious Moonsault (Z-Move)
PRIMARINA: Sparkling Aria, Oceanic Operetta (Z-move)
TOUCANNON: Beak Blast
CRABOMINABLE: Ice Hammer
ORICORIO: Revelation Dance
RIBOMBEE: Pollen Puff
LYCANROC: Accelerock
TOXAPEX: Baneful Bunker
LURANTIS: Solar Blade
SHIINOTIC: Strength Sap
TSAREENA: Trop Kick
COMFEY: Floral Healing
ORANGURU: Instruct
GOLISOPOD: First Impression
PALOSSAND: Shore Up
PYUKUMUKU: Purify
SILVALLY: Multi-Attack
TURTONATOR: Shell Trap
TOGEDEMARU: Zig Zap
BRUXISH: Psychic Fangs
DHELMISE: Anchor Shot
KOMMO-O: Clanging Scales, Clangorous Soulblaze (Z-Move)
TAPU KOKO, TAPU LELE, TAPU FINI, TAPU BULU: Nature's Madness, Guardian of Alola (Z-Move)
SOLGALEO: Sunsteel Strike
LUNALA: Moongeist Beam
NECROZMA: Prismatic Laser
MAGEARNA: Fleur Cannon
MARSHADOW: Spectral Thief, Soul-Stealing 7 Star Strike (Z-Move)
PIKACHU: Catastropika (Z-Move)
ASH-HAT PIKACHU: 10,000,000 Volt Thunderbolt (Z-Move)
ALOLAN RAICHU: Stoked Sparksurfer (Z-Move)
MEOWTH & PERSIAN: Pay Day
KADABRA & ALAKAZAM: Kinesis
MACHAMP: Strength
EXEGGUTOR: Barrage
ALOLAN EXEGGUTOR: Dragon Hammer
MAROWAK: Bone Club, Bonemerang
ALOLAN MAROWAK: Shadow Bone
CHANSEY: Soft-Boiled
JYNX: Lovely Kiss
EEVEE: Extreme Evoboost (Z-Move)
PORYGON FAMILY: Conversion, Conversion2
SNORLAX: Pulverizing Pancake (Z-Move)
MEWTWO: Psystrike
MEW: Genesis Supernova (Z-Move)
SPINARAK & ARIADOS: Toxic Thread
OCTILLERY: Octazooka
DELIBIRD: Present
SMEARGLE: Sketch
MILTANK: Milk Drink
LUGIA: Aeroblast
HARIYAMA: Smelling Salts
LATIAS: Mist Ball
LATIOS: Luster Purge
KYOGRE: Origin Pulse
GROUDON: Precipice Blades
RAYQUAZA: Dragon Ascent
JIRACHI: Doom Desire
DEOXYS: Psycho Boost
VESPIQUEN: Attack Order, Defend Order, Heal Order
CHATOT: Chatter
DIALGA: Roar of Time
PALKIA: Spacial Rend
HEATRAN: Magma Storm
REGIGIGAS: Crush Grip
GIRATINA: Shadow Force
CRESSELIA: Lunar Dance
DARKRAI: Dark Void
SHAYMIN: Seed Flare
ARCEUS: Judgement
VICTINI: Searing Shot, V-create
EMBOAR: Heat Crash
AUDINO: Secret Power
KROOKODILE: Power Trip
CINCCINO: Tail Slap
GALVANTULA: Electroweb
KLINKLANG: Gear Grind
BOUFFALANT: Head Charge
HEATMOR: Fire Lash
VOLCARONA: Fiery Dance
RESHIRAM: Fusion Flare, Blue Flare
ZEKROM: Fusion Bolt, Bolt Strike
KYUREM: Glaciate
WHITE KYUREM: Ice Burn
BLACK KYUREM: Freeze Shock
KELDEO: Secret Sword
MELOETTA: Relic Song
GENESECT: Techno Blast
CHESNAUGHT: Spiky Shield
DELPHOX: Mystical Fire
GRENINJA: Water Shuriken
VIVILLON: Powder
AEGISLASH: King's Shield
INKAY & MALAMAR: Topsy-Turvy
HELIOLISK: Electrify
HAWLUCHA: Fltying Press
KLEFKI: Fairy Lock
TREVENANT: Forest's Curse
GOURGEIST: Trick-or-Treat
XERNEAS: Geomancy
YVELTAL: Oblivion Wing
ZYGARDE: Land's Wrath, Thousand Arrows, Thousand Waves, Core Enforcer
DIANCIE: Diamond Storm
HOOPA: Hyperspace Hole, Hyperspace Fury
VOLCANION: Steam Eruption
DECIDUEYE: Spirit Shackle, Sinister Arrow Raid (Z-Move)
INCINEROAR: Darkest Lariat, Throat Chop, Malicious Moonsault (Z-Move)
PRIMARINA: Sparkling Aria, Oceanic Operetta (Z-move)
TOUCANNON: Beak Blast
CRABOMINABLE: Ice Hammer
ORICORIO: Revelation Dance
RIBOMBEE: Pollen Puff
LYCANROC: Accelerock
TOXAPEX: Baneful Bunker
LURANTIS: Solar Blade
SHIINOTIC: Strength Sap
TSAREENA: Trop Kick
COMFEY: Floral Healing
ORANGURU: Instruct
GOLISOPOD: First Impression
PALOSSAND: Shore Up
PYUKUMUKU: Purify
SILVALLY: Multi-Attack
TURTONATOR: Shell Trap
TOGEDEMARU: Zig Zap
BRUXISH: Psychic Fangs
DHELMISE: Anchor Shot
KOMMO-O: Clanging Scales, Clangorous Soulblaze (Z-Move)
TAPU KOKO, TAPU LELE, TAPU FINI, TAPU BULU: Nature's Madness, Guardian of Alola (Z-Move)
SOLGALEO: Sunsteel Strike
LUNALA: Moongeist Beam
NECROZMA: Prismatic Laser
MAGEARNA: Fleur Cannon
MARSHADOW: Spectral Thief, Soul-Stealing 7 Star Strike (Z-Move)