New Super Mario Bros.: 7-2

This is a narrow level that wraps around, so if you go off screen to the left, you'll appear on the right. Go up the pipe and get on a platform with three arrows. Stand either on the left or right sides to make the platform go in that direction as it continually ascends. To make life interesting, you'll have to contend with Parakoopas, who will walk on the platform if you stomp them once. There are narrow gaps throughout the level, and after the first one, you'll find the first Star Coin encased in brick. Break the bricks to get it. There are some Red Coins to collect before the midpoint. You'll want to stay to the right until the stairs appear, then move towards the center. Use a Koopa shell at the top of the stairs to reach the second Star Coin, so you can keep going. Towards the top, you'll find Parakoopas flanking the center of the level. The third Star Coin is over on the left side, so be careful as you try to get it. Take the pipe at the top to the goal.

Super Mario 3D Land: 7-2

We start in a room of stone with rolling spikes on chains. We die from a Chomp.
Take 2- We take a hit from a Chomp and hit the red ! block above its post. It forms stairs to the alcove with the first Star Coin. We dodge more rolling spikes to a door to the midpoint. We have to dodge rolling spikes on blue and pink platforms that tilt, making the spikes roll. On dropping platforms is the second Star Coin. We reach the end of the tilting bridge and walk up the stairs and around the corner. There are two Chomps, as well as more rolling spikes, and regular spikes. Over the spikes is the third Star Coin. We reach the stairs to the door. Behind the stairs are some coins. Beyond the door are tilting platforms to the flagpole, one of which has a rolling spike.

New Super Mario Bros. Wii 7-2 QSC

I got the first Star Coin by pounding the Chomp's stake near the first Star Coin. The Chomp will break through the blocks so you can reach the Star Coin. I got the third Star Coin by dropping out of the water bubbles between the two Chomps and get out.
118 down, 89 to go

New Super Mario Bros. Wii: 7-2 -- Weird, but Easy

This is a strange level. There are Chain Chomps and floating bubbles of water that Mario can swim in. I skipped the 1st Star Coin and reached the midgate. I went into a green pipe and got the 2nd Star Coin. I got a 1-up at the goal.