Teenage Mutant Ninja Turtles Mutants in Manhattan

The Secret Boss is Super Shredder who sometimes appears after the Shredder level boss fight. I think the criteria is to get an "S" rank on the shredder fight for him to reincarnate as a super version of him.

There's a few methods to making this happen more often.

* Set Difficulty to Easy. This means he has only 5 bars of health to work through.

* There is a secret part to the Shredder mission. If you get an S rank on all 3 elevator battles, then you will be forced to enter a Mech room where you get to use the Mech in the Shredder fight if you defeat it of course. If you have the mech, I recommend having your AI set to "Go All Out" (, then , then ). This means they will be up hitting shredder and keeping out of your way. I recommend you stand as far back with your mech as possible, Lock onto Shredder by pressing (if it doesn't lock, you might be too far away.. just go closer till it locks, then back up as far as you can), and hit him using your rockets. Just hold and his health will melt away.

* I don't really recommend this part, but I'll include it as an option for the more skilled players. If you are good with doing reverse attacks or parrys, it will speed up the fight, increasing your chance of an S rank. To do a reverse attack, you press just as Shredder is about to hit you and your turtle will spin around to his back and there will be a brief prompt of where you can jump on his shoulders and bash his head. To Parry, you hold your dodge using and then release at the point where Shredder is about to hit you it will parry and stun him, helping you defeat him quicker. The reason I don't recommend this is because it's hard to get the timing right.

There might be another boss somewhere else that's counted as a secret boss. If so, please leave a comment and I'll add it. Good Luck!