Beat dialga
Have a pikachu, chimchar or any Pokemon that can learn dig as your partner I chose Pikachu first hit dialga with a sleep seed or an x-eye seed then get you partner to use dig and BAM dialga wil take 150-230 damage if you are around lv 45.
If you need more help, we've got more Pokemon Mystery Dungeon: Explorers of Time cheats and also check out all of the answers for this game
Comments for this hint