@Shiny_Charizard of course, it can be done.
You have to go to the garc folder of the cry and find the cry of deerling and that of lugia, after which you swap the cry of deerling with that of lugia :)
( oras garc list https://pastebin.com/4bg3q6FL) ( X/Y garc list https://pastebin.com/QNCz7Avh)