I just want to make sure that my guess here is right, because it
seems like only the Rotom forms from the games (Normal, Mow, Frost,
Heat, Wash, and Fan) are required for Sinnoh dex completion, since
there are only six spots with Rotom’s Pokédex number in the Sinnoh
dex.
Castform has 18 spots in the Hoenn dex, so it seems that all of the
Emera-only forms of Castform are required for Hoenn dex completion,
but the Emera-only forms of Rotom are not required for Sinnoh dex
completion.
No, because it’s just a guess. I feel like it makes sense, but I
have no actual evidence for it. I’m looking for someone who has
completed the dex to confirm or deny it. Maybe my dex is glitching.
It does seem weird that Emera-only Castforms would be required but
Emera-only Rotoms wouldn’t (although I’m certainly hoping that at
least the Emera-only Rotoms aren’t as I just managed to get my
sixth Rotom and would like to not have to get any more).