Normally, you can't play as the boss character. He has the best drop pattern.

If you enter the Konami code at the title screen, you'll hear a jingle, and you can select him.

This hack enables him from the start, no Konami code required.

https://gamefaqs.gamespot.com/snes/571170-tsuyoshi-shikkari-shinasai-taisen-puzzle-dama/cheats

change 0x755 from AD to 8D