legendaries

How to beat Groudon: Groudon is Ground/Fire, so water type Pokemon are preferred.

How to beat Jirachi: I admit Jirachi is VERY hard to beat. My method is scouting the floors for any sleep seeds, totter seeds, and reviver seeds. At your first turn in battle use a Defence Curl to increase Defence by x2 (Cause of Bidoof's ability), then throw seeds at it.

Actually I find the best method is, getting about 3 reviver seeds before you even start the mission, star cave is riddled with tons of reviver seeds, so pick some of those up and with a few sleep seeds it should be an easy battle.

Also, groudon can will only join your team from beating the scizor special mission and obtaining the special rank, then getting the shimmer hill mission from a Pokemon in the cafe. You can only get jirachi to join your team from a specail battle request, which I believe you will get from someone at the cafe sometime after you get master rank.

Actually for Jirachi you can get the mission before the Master Rank.

I recomend lots of reviver seeds like me cause I beat the game n darkria also I got the challenge from jirachi before I beat the episode so I beat it with only some of my reviver seeds being used cause I used defence curl so many times