As far as I know, these are all the quick ways to reach 30 000 coins in Coin Rush, with one distinct method for each pack of levels.
Mushroom Pack
Make sure Mushroom 1 is the first level, then get to the yellow pipe. Go down the pipe, stun the Paratroopa bouncing around to the right and break the bricks as shown in the video. Then, turn into Gold Mario with the Gold Flower kept in the inventory, and when the Koopa gets to the right spot, jump on it to keep bouncing in place and racking up coins.
However, after 15 hits the shell breaks, so you'll need to get off and exit the area after 14 bounces to reset the whole thing.
Here's a video on Youtube showing what to do:
http://www.youtube.com/watch?v=WeaVnvp2ZrM
Do that, except as Gold Mario.
Coin Trick 2
Choose 2-4 as the first level, and get the Gold Flower from the roulette block (easy to time if you run right straight away and jump when directly under it). Now, keep going through the level until you see a yellow pipe, and go down it.
In here, you'll see lots of Goombas spawning from some pipes to the right. So make sure you're Gold Mario (if you aren't already), then bounce off the Goombas heads without hitting the ground to get an absolute ton of money.
Here's a video showing it:
http://www.youtube.com/watch?v=f7zHOlnc6tw
Flower Pack
Choose 3-4 as the first level, and keep going past the midway point flag. Now, keep going and hit the invisible block in between two ? blocks for a vine to a secret area.
In here, you'll see a Koopa walking from the right side, a gold ring and a ? block to the lower left of the screen, to the right of the flag. Go to the top, and either Raccoon Whip the Koopa so it falls down near the vine, or pick it up, throw it at the lowest block and jump on it to stop it nearby.
Now, become Gold Mario, and hang on the vine. When the Koopa wakes up and walks towards the block/you (depending on whether it's on the left or right side), go down so you hit it and it bounces off the block. Stay down at the right height, and the shell will keep bouncing off Mario's feet for infinite coins.
Here's a video:
http://www.youtube.com/watch?v=6gAZuW7Ykho
Star Pack
For this one, it's basically like the Mushroom 1 trick, except you can do it at any point in Star 1 with a Koopa nearby. Here's a video showing what you have to do:
http://www.youtube.com/watch?v=DZe0SOyrU6M
As you can see, just break the right bricks, become Gold Mario, wait for the Koopa to wake up and walk into position and constantly bounce off its head/shell until the shell breaks.
Hopefully these tricks will help you reach 30 000 coins in each of the Coin Rush level packs in New Super Mario Bros 2, they sure helped me!
Mushroom Pack
Make sure Mushroom 1 is the first level, then get to the yellow pipe. Go down the pipe, stun the Paratroopa bouncing around to the right and break the bricks as shown in the video. Then, turn into Gold Mario with the Gold Flower kept in the inventory, and when the Koopa gets to the right spot, jump on it to keep bouncing in place and racking up coins.
However, after 15 hits the shell breaks, so you'll need to get off and exit the area after 14 bounces to reset the whole thing.
Here's a video on Youtube showing what to do:
http://www.youtube.com/watch?v=WeaVnvp2ZrM
Do that, except as Gold Mario.
Coin Trick 2
Choose 2-4 as the first level, and get the Gold Flower from the roulette block (easy to time if you run right straight away and jump when directly under it). Now, keep going through the level until you see a yellow pipe, and go down it.
In here, you'll see lots of Goombas spawning from some pipes to the right. So make sure you're Gold Mario (if you aren't already), then bounce off the Goombas heads without hitting the ground to get an absolute ton of money.
Here's a video showing it:
http://www.youtube.com/watch?v=f7zHOlnc6tw
Flower Pack
Choose 3-4 as the first level, and keep going past the midway point flag. Now, keep going and hit the invisible block in between two ? blocks for a vine to a secret area.
In here, you'll see a Koopa walking from the right side, a gold ring and a ? block to the lower left of the screen, to the right of the flag. Go to the top, and either Raccoon Whip the Koopa so it falls down near the vine, or pick it up, throw it at the lowest block and jump on it to stop it nearby.
Now, become Gold Mario, and hang on the vine. When the Koopa wakes up and walks towards the block/you (depending on whether it's on the left or right side), go down so you hit it and it bounces off the block. Stay down at the right height, and the shell will keep bouncing off Mario's feet for infinite coins.
Here's a video:
http://www.youtube.com/watch?v=6gAZuW7Ykho
Star Pack
For this one, it's basically like the Mushroom 1 trick, except you can do it at any point in Star 1 with a Koopa nearby. Here's a video showing what you have to do:
http://www.youtube.com/watch?v=DZe0SOyrU6M
As you can see, just break the right bricks, become Gold Mario, wait for the Koopa to wake up and walk into position and constantly bounce off its head/shell until the shell breaks.
Hopefully these tricks will help you reach 30 000 coins in each of the Coin Rush level packs in New Super Mario Bros 2, they sure helped me!