World 6-A: Prince Bully Blockade
To take our Prince Bully, you have to knock him into one of the pipe openings along the wall. This will compress him, and he'll pop out of another opening as a little cylinder, vulnerable to attack. Hit him three times in this state to defeat him and earn a star.
World 6-5: Ty-Foo Furies
Stamp: Ice Skate Mario
Jump onto the Skating Goomba near the beginning of the level to grab the Ice Skate. Skate out onto the spikes nearby to find this there.
Now head to the ledge above the spikes. By the second Ty-Foo is a pair of bricks with a hidden brick above them. Use these to reach the star in the air above.
Grab an Ice Skate from a Skating Goombas on the ice just past the checkpoint. Use it to cross the spikes to the left side of the area and reach a mystery box. Inside, you have ten seconds to grab another Ice Skate and move through the obstacle course. There's a star at the end.
The last star in the level is very tricky to grab. Jump when the wind is whipping, and it carries you over the star. Jump when the wind is clear, and you'll fall to your death. A few wisps appear in the pit just before the wind kicks up - jump when you see them to grab the star and be saved by the wind.
World 6-6: Bullet Bill Base
Using the Cat Suit, you can make your way to very top of the first base. There's a star waiting there.
When you reach the second base, scramble up the first wall to find a mystery box. Inside, you have ten seconds to grab a star hovering by a rotating wheel. Use the Cat Suit to quickly scramble your way there.
When you reach the set of four conveyor belts, use the Cat Suit to scramble up the one on the far left. Ride it up, then ride the next one to the right. This takes you to a ledge with a star.
Stamp: Stunned Goomba
The stamp is on the final platform overlooking the flagpole. You simply have to jump onto the row of bricks, then jump up to the stamps. If you happen to break the bricks, you can still reach the stamp with a spin jump from the raised ledge.
World 6-7: Fuzzy Time Mine
This is found early in the level. When you reach the first horizontal retracting platform, you'll spot it inside the dip.
You'll see this on the right side of the level just past the stamp. Use a ground pound to bust through the cloud and reach it.
When the stage starts scrolling to the right, you'll find this on the first seesaw.
At the final stretch of the stage are four pairs of horizontal retracting platforms. Use the jump pad to reach the space behind them - there's a star here.
World 6-Special: Mystery House Throwdown
You have ten seconds to complete each room's challenge. For the first, quickly chuck a baseball down the slope. The ball rolling into the star counts as picking it up.
Immediately jump once in the second room to flip the panel to red. Now grab a baseball and jump. As the panel flips to blue, chuck the ball into the star.
In room three, grab a baseball and use the jump pad. Move forward while doing this to practically dunk the basketball into the switch on the wall, summoning a star.
The fourth room is full of Para-Biddybudds. Use baseballs to hit the POW Blocks and clear them out. This spawns a star.
In the final room, there are three question mark tiles guarded by Thwomps. Quickly chuck baseballs at the three tiles when the Thwomps rise to summon a final star.
World 6-Castle: Bowser's Bob-omb Brigade
When this series of eight question mark bricks rolls by, toss a Bob-omb. This activates a series of platforms that will help you reach the star above.
When the path splits, grab a Bob-omb and run at the bottom right vehicle. Use the Bob-omb to destroy the big brick here, revealing a star.
When you reach the caravan with stacked coins, there will be a question mark brick on the left side of the vehicle. Smack it a few times (a Tanooki Suit tail works best) to extend additional bricks to the right. Use these to reach the star suspended in the air.
Stamp: Wind-Up Soldier
When the final vehicle rolls up, save a Bob-omb and throw it all the cracked Bowser wall behind the warp pipe. There's a stamp back here.
World 6-C: Motley Bossblob's Big Battle
Defeat Motley Bossblob to receive this star.