Castform hasn't been the easiest, I was able to figure out a way to disable his transformation with weather.. all that really does though is prevent his animation from breaking though. I'm still searching, I don't think this will be to easy though from the information he has 12 form switches... *likley one for each form sunny --> hail, hail ----> rain, rain -----> sunny, ect) or maybe I'm crazy and confused xD
Deoxys wasn't hard considering his form is set depending on the version..