Super Mario Galaxy 2 is one of the best games ever! You'll need 70 stars to defeat bowser, but to be a true Mario grandmaster you've got to collect all 120 gold and a further 120 green stars. That's not so easy, and these are a few of the handy cheats for beating the game.
Quickly Grab 99 1-Ups at Supermassive Galaxy
This is a great cheat with which you can rack up the maximum 99 1-Ups within a couple of minutes whenever required. Thus, the cheat (can be seen on the video below) pretty much gives you an infinite number of 1-Ups. First, head over to Supermassive Galaxy and select to play the first (far left) star challenge at that galaxy. Play through that galaxy until you get to a tiny planet with three giant Koopa turtles on it.
Don't pick up the Spin Drill there. Instead, do a long jump (by holding the Z button while running and jumping) onto the back of one of the turtle's shells. Hold the jump button to keep jumping on the back of the turtle's shell. After a few jumps, you'll start to rack up 1-Ups for each jump on the Koopa's shell.
Get 99 Lifes Aboard Starship Mario
Alternatively, you can stack up the maximum 99 lifes aboard Starship Mario. This cheat is a little slower than the Koopa cheat, but you can still stack up loads of 1-Ups nonetheless. When you've unlocked Luigi (by checking the Mail Toad after beating Bowser at Galaxy Generator), collect the 1-Ups aboard Starship Mario and then enter the door on the startship with the L above it. Every time you enter that door to switch between Mario and Luigi, all the 1-Ups on the starship come back for you to collect again.
If you haven't unlocked Luigi, you can still stack up on 1-Ups aboard Starship Mario without him. Collect all the 1-Ups aboard the ship and fly onto the galaxy map. Then return to the Starship Mario. When you've returned to the starship, all the 1-Ups will be there for you to collect again. Thus, you can also collect up to 99 lifes by flying the starship on the galaxy map and then returning to the ship.
You can collect about six 1-Ups on Starship Mario every time you switch between Mario and Luigi. Rolling the Chance Cube on the starship might get you a 1-Up. You can collect a 1-Up by walking into the transporter that takes Mario to the Starshroom. Both the Gearmos at the teapot table will also give you 1-Ups when you chat with them.
Unlock Luigi's Ghosts For All Galaxies
Luigi ghosts appear in galaxies for players to race against when you unlock them. Those ghosts are more like recordings of the game's designers completing the galaxies. To unlock all the ghosts, you would usually need to play through all the galaxies with Luigi. However, if you can't be bothered to play through every galaxy, you can instead unlock all the ghosts by collecting 9,999 coins instead.
Turn Coconuts into Watermelons
This is a fun cheat Nintendo has carried over from the original Mario Galaxy. The cheat turns all coconuts in galaxies into watermelons! To activate the cheat, you'll need to collect 9,999 star bits. As such, you'll need to save plenty of star bits by depositing them at the banker Toad aboard Starship Mario.
Quickly Stack up 9,999 Star Bits
If you're looking for a quicker way to amass 9,999 star bits, head over to Yoshi Star Galaxy. Collect all the star bits on the first stage of that galaxy, and then spin the star that propels Mario over the erupting volcano to a small planet where you can collect more star bits. Do not run through the flag checkpoint on that second planet. Instead, jump into the star and then kill off Mario on a spiky plant on the third planet.
That will return you to the beginning of the galaxy where you can collect a 1-Up to replace the lost life by stepping into the teleporter that takes Mario to a floating platform with Octoombas on it. There quickly spin or stomp on all the Octoombas to collect up to three 1-Ups. Thereafter, you can collect all the star bits on the first and second planets of Yoshi Star Galaxy, kill off Mario on the third planet and then collect the 1-Ups again any number of times to rack up to 9,999 start bits before you finish the galaxy.
Get Extra 1-Ups From the Banker Toad
The banker Toad will show off his gear whenever you deposit a certain amount of star bits. He'll show you glasses, a spear and shield, a pickaxe, a scuba outfit and an explorer outfit when you deposit 1,000, 2,000, 4,000, 6,000 or 8,000 star bits. Banktoad will also throw in a few 1-Ups when you deposit those star bit amounts.
Note that you also need to deposit the maximum 9,999 star bits to unlock the Perfect Run Galaxy. That's the very final mission on the Grandmaster Galaxy where you can collect the 242nd Power Star, which is the crowing moment for any Mario Galaxy 2 fanatic!
Of course, you're a Mario Galaxy 2 grandmaster when you've completed Grandmaster Galaxy. The above cheats and tips will come in handy for first beating bowser and then collecting all the stars.