Non-default Silvally formes do not show Type: Null as a previous evolution

[alaserdolphin]

To my understanding, this was a result of previous code cleanup - I believe it was discussed that the best plan would be to probably just hard-code all of the Silvally-* to allow T moves in Alphabet Cup.

I linked the clause here for ease of access

If possible, it'd also be appreciated to have the name of the clause shortened from Alphabet Cup Move Legality to Alphabet Cup. Not that it's a huge deal, but CUSTOM-RULES.md also doesn't mention the clause currently.
I understand that they're not inherently connected, but they're small/trivial enough that submitting them as a separate issue felt overkill.

Thanks!