Legal Alpha Decidueye captured in game as its pre-evolution. Is shown not legal for some reason (I didn't modify it). https://imgur.com/a/0bmHaQT
My guess is that it doesn't check if it has been captured as pre-evo.
PK8 file: https://mega.nz/file/kEsyGZxK#NVuV1e83ZNk1jfStmFhI2JgNKH2cLljyJ8r9EulkvIw