I received Ganbare Goemon- KiraKira Dochuu a few days ago. So far, I'm loving the game. The level design is very creative with the Goemon wackiness in full force. One section has Goemon riding downward on a soccer ball while avoiding spikes and guys with baseball bats. Another section of the game has a gun with crosshiars that aims at you that looks strangly familiar. I don't want to reveal too much becuase some of this stuff is much more enjoyable if you don't say too much about it first.
The major bosses all have their own minigames, but I only encountered two of them so far. One of them is Taisen Puzzle Dama. The other one encounters trying to catch a sword from a diving mech. Apparantly, the mini games can be unlocked to be played seperate from the main game. There is also an extra game named Time Pilot '95 that can be unlocked, that isn't from a boss. Since this game was used, the mini games were already unlocked when I got it, including Time Pilot '95. The version of Taisen Puzzle Dama that is outside of the main game has vs. CPU vs. 4 characters with good AI. It can be played with up to four pltyers. Time Pilot '95 is just Time Pilot with improved graphics. Still, the original Time Pilot is a sweet game, so a good version of it as an unlockable is very sweet.
Edit: The version of Taisen Puzzle Dama in the game isn't quite full fleged, but it's still great fun.