Unlimited magic butterflies:Go to the cave in Onett and find the location where you can see the giant step but cannot get to it. Keep entering and exiting this location, heal yourself, then get more butterflies as needed.

Find the hole in the ground in the maze of tunnels under Tenda Village. Use it to drop down to a small cavern with a black talking rock and a butterfly. The rock will say similar to 'You're in the Earth's belly button'. Get the butterfly, then walk just far enough out of that room so the rock is no longer visible. Walk back in and the butterfly will re-appear. Keep collecting the butterflies as needed for full HP and HPP.