If you click my Solgaleo, it says it is a stage 1 Pokémon even though it should be a stage 2 Pokémon
I think that's because Cosmog is classified as a Baby Pokémon, not a Basic. Cosmoem is the Basic ^^
I know this is old, but adding onto this- Cosmog shouldn't be classified as a Baby Pokemon.
https://bulbapedia.bulbagarden.net/wiki/Baby_Pok%C3%A9mon
It isn't on the list of Baby Pokemon
Cosmog should be a Basic Pokemon, Cosmoeum should be stage 1, Solgaleo/Lunala should be Stage 2.