Ok, this one is good
Tested using both "[Help]" to "Skip Level" or "[Del] to "Skip World", you see the code protection screen but can enter in anything, then the game continues
...as mentioned previously, the only bad thing with the trainer is that when you skip the level before the boss, the boss level loads and it gets killed immediately. You don't get the chance to actually engage / destroy it
This happens both in "Story" and "Arcade" mode unfortunately...