From the Super Mario Wiki
Mario Hoops 3-on-3 -- Dribble Skillz is an online Flash game originally published on the official Mario Hoops 3-on-3 website. It was also listed and playable in the Nintendo Arcade, a section on nintendo.com, among other promotional web games.
The objective of the game is to dribble several basketballs for as long as possible, using Mario's hand which is controlled with the mouse. The player can only move the hand horizontally and the game starts with only one basketball to dribble. More basketballs gradually spawn, demanding better timing to catch all of them. Each time a ball bounces off the floor, the hand has to send it back. For every dribble, 10 points are added to the score.
The player should aim to hit the ? boxes that appear on the ground, which give one coin at each hit; whenever the ? box is hit a fifth time, it gives five coins and warps to another spot on the ground. Coins do not increase the score, but are added to a separate coin counter. Sometimes, Green Shells appear and slide across the field, and if hit by a ball, they deduct 50 points from the score and disappear, causing the ball to move faster for the moment. 1-Up Mushrooms also appear, although less often, and move across the court; hitting one with a ball adds another life and 100 points.
The player is given five lives, which they lose one by one if they miss catching the basketballs. After the game is over, the player is shown the final score, which is the product between the in-game score and the number of coins earned.
Coins collected in the game could be used on the official website to unlock characters, which could then be dragged on a field and selected to read snippets about each.