World 5-1: Sunshine Seaside
At the start of the level are three Goomba sand sculptures. Destroy all three with ground pounds, Koopa shells, or your weapon of choice to earn a star.
This tricky star is actually in the water. Look along the northern edge of the level to spot a pit. Take a dive and use the warp pipe to reach a well hidden area. Hit all the tiles inside before the music stops to earn a star.
Past the second set of sand sculptures is a little alcove. Backflip into this to find Toad being chased by Billybuds. Take them out to save him and earn a star as thanks.
Stamp: Koopa Shell Kick
You can get this while riding Plessie. Just before the course ends, bear right to reach some wooden platforms. Hop across these to grab the stamp at the end.
World 5-2: Tricky Trapeze Theater
When grab onto the trapeze above the spiked roller, leap to your left to land on some clouds. There's a star on the ledge up here.
To the right of the wheel of Piranha Plants is a warp pipe. Head through and hit the blue switch. Collect the three series of blue coins that appear to spawn a star.
Stamp: Jumping Luigi
This is on the left side of the stepped platforms immediately after the wheel of Piranha Plants.
After riding through the clear pipe, you'll come to a hollow green star by series of trapezes. Hit the star to spawn eight green coins, then quickly traverse the trapezes to collect them and earn a star.
World 5-3: Backstreet Bustle
There's a cracked tile to the left of the level's start. Ground pound it to reveal a star.
To get this, you'll need to create Double Cherry four clones from the question mark bricks.
Stamp: Little Toad
There's a Toad switch on the right side of the course. Use Toad to hit it and spawn a stamp.
Take three Double Cherry clones to the three-man platform in the middle of the level to reach this star.
World 5-A: Chargin' Chuck Blockade Is Back
You'll have to battle five Chargin' Chucks this time. Take them out to earn a star.
World 5-4: Sprawling Savanna
When you reach the first wall with multiple clear pipes, use a Cat Suit if you have one. Scramble up the left side of the wall to find a star in a little alcove. Be aware of the hidden bricks underneath it.
When you reach the titular savanna, you'll spot several rabbits in bushes in the middle of the area. Chase after the one with a green glow; catch him to earn a star.
Stamp: Cat Suit Peach
On your way out of the savanna, stop by the parading Ant Troopers. Drop into the hole they are headed towards to reach a hidden area. The stamp trails behind a Giant Ant Trooper in here.
At the very end of the level are two rotating walkways and a hollow green star. Hit it to spawn eight green coins. Collect all eight to earn a star.
World 5-5: Bob-ombs Below
You'll come across a POW Block early in the level. Hit it with a Tanooki Tail Spin or a Bob-omb throw to destroy the purple bricks and reveal a star. Alternatively, you can just break through the bricks themselves.
Immediately after the checkpoint is a rabbit on a rotating platform. Chase him down to earn a star.
After the rabbit are two stacks of Goombas carrying bombs. Use a bomb to bust through the cracked wall nearby, then use the other to hit the POW Block and reveal what was behind that wall: a stamp. Hop back and grab your prize.
When you ride the last clear pipe, bear down to hit the lower path and reach a cloud that launches you to a secret area (you can also use the Tanooki Suit to hover jump to the cloud). In the secret area, step on all the tiles before the music ends to earn a star.