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
Frillish was released with the start of the second half of GO Battle League Season 6.

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

February
Mega Gyarados was released on Lunar New Year 2021.

Regular (1) =

Shiny (1) = PS Gyarados

February
Munna was released on Valentine's Day 2021.

Regular (2) =

February
Shiny Spearow, Paras, Hitmonlee, Hitmonchan, Ditto, Snorlax and Mew released on Pokémon GO Tour: Kanto.

Please note that some of them might be released before the said event. Shiny (9) = PS Spearow PS Fearow PS Paras PS Parasect PS Hitmonlee PS Hitmonchan PS Ditto PS Snorlax PS Mew