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 has 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.

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

March
Shiny Landorus was released. Female Frillish was also released in this day, being only the male version available before.

Shiny (1) = PS Landorus

March
Shiny Tornadus was released, and Shiny Fletchling was released on 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