Go to the option menu, highlight "credit" and press select for 10 times. The values of the credit will become 50.
Go to the title screen and highlight "Vs mode". Press and hold L and R, then press A. This should bring you to a hidden screen, highlight "Who" and choose your character. You will be able to fight as Colon or Happy.
At the title screen, highlight 1 Player mode (Vs. CPU) and press Start on both Controller 1 and Controller 2. If done right, the ending will start right away.