I'll just leave this here. This method will work with a bit of luck. I was able to manage it with a decent second player... it still makes your ass sweat but damn.. what a feeling!
If one of you goes down, revive immediately. Punch and kick your way into super power mode and mop up the screen. Watch the Knights, Yellow Rangers Y ability in super power mode is very effective against them. I used the Green Ranger as he seems to deal the most damage, Yellow Ranger for speed and her Y super power ability.
This shouldn't give you much pain. Stick with it and have some fun!
YOU ONLY NEED TO GET TO THE 50TH FLOOR, YOU DO NOT HAVE TO BEAT IT!
Not my video all credit to UrbanmonkeyPSS