Can a Pokemon remember a move they previously had, but are not normally able to learn?
Right now, you can get a Pikachu with Fly via a https://www.serebii.net/events/dex/025.shtml#2022 . Obviously, Pikachu is not normally able to learn Fly. If I accidentally tell Pikachu to forget Fly, will he be able to remember that move? Or do I need to be very careful about what moves he learns?
In Gen IX, it seems Pokemon can re-learn any move they ever knew, even if it's from a TM or an event. As demonstrated in the screenshot (Move was forgotten beforehand.)