From what I know, Wyrdeer is super good with the crest, and pretty good without it. I'd say Delpha and delphox are the same mon (and besides, why would you want to use delphox when you have an objectively better version available earlier)
Personally I'd allow the crests, so long as they have the psychic type (for example, Darmanitan is Fire/Psychic, and Gothitelle and Reuniclus start as psychic types)