Just to know why it's only legal when the save is named sav.dat and not any other name, as PokemonCrystal.sav?
If it's legal for one, it should be for the other one, no?
I know it's because the event got only released on virtual console versions and they use the sav.dat name, but meh, as I said, it's a legal celebi in both case, if it just depend of the save's name, the pk2 file doesn't differ.
Could you add a legality check that doesn't depend on the save's name?