List of Pokémon forms by release date/2021

January
Genesect Burn Drive and shiny Snivy were released on Unova Celebration Event.

Regular (1) =

Shiny (3) = PS Snivy (495) PS Servine (496) PS Serperior (497)

January
Male Frillish was released with the start of the second half of GO Battle League Season 6. Female form had not been released yet.

Regular (2) =

January
Shiny Buizel was released with the start of the Sinnoh Celebration Event.

Shiny (2) = PS Buizel PS Floatzel

January
Mega Ampharos was released.

Regular (1) =

Shiny (1) = PS Ampharos

January
Shiny Miltank was released with the start of the Johto Celebration Event.

Shiny (1) = PS Miltank

February
Mega Gyarados was released on Lunar New Year 2021.

Regular (1) =

Shiny (1) = PS Gyarados

February
Munna and shiny Spinda pattern 9 and Alomomola were released on Valentine's Day 2021.

Regular (2) =

Shiny (2) = PS Spinda PS Alomomola

February
Shiny Spearow, Paras, Hitmonlee, Hitmonchan, Ditto, Snorlax and Mew were released on Pokémon GO Tour: Kanto. Since then, all the Shiny Pokémon of Kanto were available.

Shiny (9) = PS Spearow PS Fearow PS Paras PS Parasect PS Hitmonlee PS Hitmonchan PS Ditto PS Snorlax PS Mew

March
Shiny Landorus and Spring form Deerling were released. Female Frillish was also released on this day, being only the male version available before.

Regular (2) =

Shiny (1) = PS Landorus

March
Shiny Tornadus was released, and shiny Fletchling was released on its Community Day.

Shiny (4) = PS Tornadus PS Fletchling PS Fletchinder PS Talonflame

March
Shiny Nosepass was released on the Searching for Legends.

Shiny (2) = PS Nosepass PS Probopass

March
Shiny Thundurus was released.

Shiny (1) = PS Thundurus

March
Mega Manectric, Therian Thundurus and Tynamo were released at the start of the Charge Up event.

Regular (5) =

Shiny (1) = PS Manectric

March
Shiny Rainy Castform was released on Weather Week.

Shiny (1) = PS Castform

March
Therian Tornadus was released.

Regular (1) =

April
Mega Lopunny and shiny Bunnelby was released on Spring into Spring.

Regular (1) =

Shiny (3) = PS Bunnelby PS Diggersby PS Lopunny

April
Therian Landorus, Skrelp and Clauncher were released on Rivals' Week.

Regular (5) =

April
Binacle and shiny Trubbish were released on Sustainability Week.

Regular (2) =

Shiny (2) = PS Trubbish PS Garbodor

April
Shiny Smeargle was released on New Pokémon Snap Celebration.

Shiny (1) = PS Smeargle

May
Spritzee, Swirlix, Goomy and Xerneas were released on Luminous Legends X.

Regular (8) =

May
Pancham and shiny Galarian Ponyta were released on the second part of Luminous Legends X. Regular (2) =

Shiny (2) = PS Ponyta PS Rapidash

May
Mega Altaria was released after May 2021 Community Day.

Regular (1) =

Shiny (1) = PS Altaria

May
Yveltal was released on Luminous Legends Y.

Regular (1) =

May
Sylveon and shiny Galarian Zigzagoon were released on the second part of Luminous Legends Y.

Regular (1) =

Shiny (4) = PS Zigzagoon PS Linoone PS Sylveon PS Obstagoon

May
Mienfoo was released with the start of GO Battle League Season 8.

Regular (2) =

June
Galarian Slowpoke, Mega Slowbro and its respective shiny form were released with the start of A Very Slow Discovery event.

Regular (3) =

Shiny (1) = PS Slowbro