There are 35.(+the 100 coins in each 15 stages)
you finish the game by beating all the levels (including canons), beating bowser, getting all the pathways, and getting all the star coins.
you get coins
Waluigi by getting 80 stars and beating the red coins and switch on bowser in the sky and go to the empty room
On Super Mario sunshine, the golden birds can be found in all levels. Simply visit the mini-stages and find a red switch on each level. Ground pound the red switch and make 8 coins appear. Collect the 8 coins before the time expires to get a golden bird.
It takes 5000 coins for the gold wheels in Mario Cart seven
he collects coins
1800 coins
10996-yoshi & mario
Yes, there is a world 9 in the game. You unlock it by beating the final boss. To unlock each level, you have to collect all of the Star Coins in the worlds of each level's corresponding second number (so for example, for 9-1, you have to collect all of the Star Coins in world 1).
203 star coins
mushrooms, princess peach, and coins