Pokémon Mystery Dungeon: Explorers of Time Tips

Aegis Cave- Beating Regigas
Once you have saved manaphy, and before you meet team charm. Go to the beach and meet lapras. brave the many dungeons and defeat dialga.

Before going to aegis cave make dialga the leader. Then when you get to regigigas, use roar of time 4 times, get close to him and use dragon claw as many times as needed.