Ganbare Goemon 3 - Shishi Juurokubei no Karakuri Manjigatame

Turn into a vase:
Press A + L + R in two player mode to turn into a vase that orbits around the other player. This can be used to play the levels without hurting your partner.

Alternate costume:
Hold Attack when changing characters to get a different color.

Hidden Boss and alternate ending:
Collect all forty four Cat Statues. Note: Twenty of them are hidden in the Overworld and there are four more in each stage.