i wanted to get a shiny Charizard on xy and wanted to know if I could trade it over to Ultra Moon. It says on the disc case that Ultra Moon can only trade to Sun and Moon games. I looked on Youtube for help and someone manege to trade a shiny Medicham over to Ultra Moon from XY. I am very confused.
You can.
Send your Pokémon from XY to Pokémon Bank, and then from Bank to Ultra Moon. Bear in mind that this is a one-way transfer, even if the Pokémon in question existed in the previous generation. Bank will identify Pokémon that have been into a Gen 7 game differently and will prohibit being transferred from Bank to Gen 6.