16 Hearts on Shredder's level
At the password screen enter 1HHHHH2. After you enter it you will have 16 hearts and be on Shreder's level

Always have 2 continues on passwords
On the last spot on the password you can always put 2 on the end no matter what password you got and get 2 continues.

Passwords

Level	Password
Before Scratch	1000002
After Scratch	2100002
After Card 1	4110102
Before Dirtbag	1111102
After Dirtbag	2311102
After Raphael	3311302
After Card 2	4331302
Before Triceraton	1311302
After Triceraton	2711302
After Donatello	3711702
After Card 3	4773702
Before Scale Tail	1777702
After Scale Tail	2H77702
After Splinter	3H77HO2
After Card 4	4HH7HO2
Before Shredder	1HHHH02