From the Super Mario Wiki
Intense Coincentration is a minigame in the game Super Mario 64 DS. In this game Wario hits a Moneybag into the sky. The Moneybag then falls to the ground and drops some Coins; however it drops less coins then in Coincentration. All of the coins will then fall to the lower floor where multiple Brick Blocks are. The coins will fall into different Brick Blocks. Then the player must touch the blocks that coins fell into with the Stylus. If a block without coins in it is touched, the game will end and any coins the player found up to that point are added up and become the player's score. A Rabbit, once caught from the castle, unlocks this minigame.
 In-Game Instructions
There aren't as many falling coins this time around, but that won't stop Wario. Watch the coins carefully!