Here are the items and powerups in the game
Coin: The most common item in the game, get 100 for an extra life.
Red Coin: Collect 8 Red Coins when you pass a red ring, if you collect all red coins, you get a power up or an extra life.
Blue Coin: get a blue coin and you get 5 coins!Green Shell: hold it for great swimming, or kick it.
Red Shell: hold it for greater swimming than green shells, kick it or make yoshi breath fire.
Blue Shell: kick it, holding it for even faster swimming or getting the yoshi wings.
Yellow Shell: kick it, holding it for the fastest swimming or making a yoshi ground pound.
Flashing colored Shell: gain all 3 shell ablities when yoshi eats it.
Hammer Bro Platform: when a afhb is defeated, you can ride the platform it was on.
? block: get a coin or item from it.
Buzzy Beetle shell: acts he same as a green shell. but you can only hold it or kick it.
Gold block: hit it and get loads of coins.
Gold Shell: when the shell hits an enemy, you get 5 coins as well as getting some in the trail it makes.
1up Mushroom: increases your lives by 1.
3up Moon: increases your lives by 3.
Super Mushroom: turn into super mario, luigi, peach or bowser.
Fire Flower: turn into fire mario, luigi or peach. you can shoot fireballs.
Super Leaf: turn into racoon mario or luigi. you can use the tail and fly.Frog Suit: turn into frog mario, luigi or peach. you can swim faster.
Tanooki Suit: as well as turning into tanooki mario peach or luigi, you turn into a statue too.
Hammer Suit: turning into hammer bro mario luigi or peach maks you throw hammers.
Yoshis power ups
Bowsers power ups