Since like 40% of you are asking how to beat it,here is the information your looking for.
1. do lots of georama in sindain and go to the future. jurak will give you an item called lafriesha seed.
2.you find out there are monster badges. they can change you into monsters. buy the himmara (looks like a yellow flower) badge at the tailor for just 500 gilda. go to the first level of rainbow butterfly wood and find a himmara DO NOT kill it. change into the himmara using the badge. talk to the himmara by walking up to it and press X. it will give you sun dew.
2.
get out of the level and buy breads and stuff that will help you fight a boss. go to the boss floor in rainbow butterfly wood. go to the pond there and put the lafriesha seed there. there will be a sprout in the pond. use the sun dew and the spout turns to a flower. go on the flower and you find the rainbow butterfly.
3.BOSS:Rainbow butterfly
be your strongest character (not ridepod!) attack the yellow things in the middle of the flower and the rainbow butterfly will split into colors.the game will give you a hint that says to walk up to the butterflies slowly and attack them in some order. the order is to attack the butterflies in the colors of the rainbow. do this and the rainbow butterfly is defeated!