wow is all i can say, definetly hard as can be, just beat it and i got the X-Force Costume, which is SOOOOO sweet, this is what i did, trust me your gonna get frustrated if you haven't already.

1-14: all ninja's get them on the floor by pressing square on them 4 times, then immediatly mount them and press square 3 times, then triangle to hammer down on them, by now you should have 1 and a half rage bars full so immediatly hit a ninja and as soon as it fills, rage mode,i know the higher the rage the more damage you do but the slow-mo in rage mode is all worth it.

15-29: first priority is to go for the gunners since they bullets are pretty hard to dodge,same mounting tactic as with the ninjas but as soon as you kill it, roll outta the way cus the other gunner should be shooting you by now, rinse and repeat by mounting and dodging and as soon as the meter fills to go into rage mode, do so, dont get it to three or four,use it as soon as you get it.

30-50: here's where the fun starts, go for the gunners and hovering robots while rolling outta the way when the big robots are swinging and firing, when the bar fills, use it on the robot, a big help in this that helped me right at the end(was at 48 and i couldn't take another hit) grab the hovering robot with the L and aim it in the direction of the big robot, if done right it should fill your rage a good 1 bar and a tiny portion and should desimate a fourth of the big robots health.

took me around 70ish tries around there, but atleast its done, also sorry to be a little of course with the names of the enemies, but i have my psp hacked and downloaded the game, i didnt buy it so i dont have the player's manual that has all the info on controls and enemy names. Hope this helps ya =)