Villains that did appear in the movie: https://thelegomovie.fandom.com/wiki/The_LEGO_Batman_Movie
Villains that should have appeared in the movie:
White Rabbit
Victor Zsasz
Mad Hatter
Tweedledum and Tweedledee
Query and Echo
Black Mask
Shriek
Cluemaster
Arkham Knight (Astrid Arkham)
Villains that I'm glad were not in the movie:
Deathstroke
Lady Shiva
Nobody
Hush
Lincoln March
Carmine Falcone
Court of Owls
Wrath
Ra's al Ghul
Talia al Ghul
Heretic
Onomatopoeia
Arkham Knight (Jason Todd)
Why are these villains on the same side?
Catwoman and everyone else
Bane and everyone else
Joker and Riddler
Calendar Man and Riddler
Kiteman and Riddler
Poison Ivy and all the male villains
(Dark Knight Trilogy perspective) Joker and Two-Face
(Arkhamverse perspective) Scarecrow and Killer Croc