This is a pretty tough puzzler, but with this code, you can win any stage! Start a stage, then press Start to pause. When you have done this, press and HOLD Select, and press Start again, unpausing. Hold BOTH buttons down as you unpause, and keep them held for about five seconds. You should see the level clear screen spring up. This is not an easy code to pull off, but it's worth it.
Password To Level 99
At the password screen type in R61H and you'll be at level 99.