Mario & Luigi: Superstar Saga Easter Eggs, Secrets and Glitches (GameBoy Advance)

Mario & Luigi: Superstar Saga features a unique battle system similar those of Super Mario RPG and Paper Mario in which timed button presses are crucial to both increasing damage of party attacks and reducing the damage of enemy attacks. This system, however, is even more important in Superstar Saga, as well-timed button presses can not only increase damage done by attacks, but also completely avoid or even counter enemy attacks as well. In terms of gameplay, Mario & Luigi: Superstar Saga differentiates itself from most other role-playing games mainly due to the amount of interaction that is required between Mario and Luigi. Unlike Paper Mario, "Superstar Saga" requires active and continual cooperation between the two main characters in order to solve environmental puzzle as well as during battle. Where this game differs is to how much correlation there is between the two. For example, gaining an ability in the overworld will also unlock a new skill in battle.

Easter Eggs

Game references in the Yoshi theater!
In the lobby of the Yoshi theater, there are four posters on the wall referring to Nintendo video games:

1. Kirby Story - referring to the Kirby series

2. Wario poster - referring to the Japanese box art design for "WarioWare, Inc.: Mega Microgames"

3. M&L - referring, of course, to this game (more specifically to the game's originally intended title, "Mario & Luigi")

4. Legend of Stafy - referring to a Japan-only game series of the same name

See Princess Peach's Castle
Go to the summit on HooHoo Mountain, walk to the top right of the summet until you get to the edge. There should be a slant in the summit shape (like an octagon) and two stone sharp-like rocks, walk up to the top one and look underneath the B button icon, you should see Princess Peach's Castle from Super Mario 64.

Glitches

Music from one place to another
Before entering a pipe, enter it with Mini-Mario. During the Pipe-Selection Screen, the music in the previous area you were just in will stay the same. When you warp to your destination, the music in the pipe will now be the BGM until you leave the area/go into pipe while not Mini-Mario, etc.

Permanent Red Pepper Effect!
Red Peppers increase your power for a few turns. During the effect, let the effected brother get knocked out. Then, use a 1-UP Mushroom to revive them. The effect will continue for the whole battle and not wear off! This is especially useful against hard bosses.

Unmovable Mario
Turn Luigi into a surfboard and surf to the coast on the east side of Beanbean Castle Town. Surf in and land on the shore. While Mario is dismounting the surfboard, hit a Bob-omb to start a battle. When the battle is over, Mario will be frozen in the air, but the pause screen will still be accessible.

Secrets

Discount on Taking Pictures!
In the Beanbean Castle area, there is a photographer that will take pictures for your passports for 100 coins. He will ask you to pay 100 coins. Say "No", and he will offer to take them for 50 coins.

Extra damage on Fire Bros
During the normal version of the attack "Fire Bros.", try abd count how many fireballs Mario conjures up. Smack the fire back, but be sure to MISS the action command on the last one. You'll do more damage in the last part than normal. You'll want to be pretty precise here, because going too early or late will hinder the total damage done.

Getting Beans Early
Normally in the game, you are unable to get any Beans until you reach Chateau de Chucklehuck, but this trick allows you to earn them in battle as early as Hoohoo Village. When you first arrive in Stardust Fields you will have to win a round of the Border Jump to enter the Beanbean Kingdom. Once you have done that, re-enter the Boarder Crossing Station, where you be asked to try the Border Jump 2. Say yes, it is a mini-game, and once you have beaten it, you will win 2 Hee Beans. Receiving these beans unlocks a new screen in the Item section of your suitcase. When this screen becomes available to you, the games programming changes to allow you to win beans as items obtained after battles.

Guess the real Cackletta
When Cackletta divides into 3, use any item, but don't attack. When the Cacklettas attack, you will see one use the left arm only, and right arm, and both arms. Attack the one that uses both arms.

Infinite Hoo, Woo, and Chuckle beans and status.
There is an Island Surfing game somewhere near Oho Oasis. After getting 1st prize (Casual Coral), you can fulfill the same criteria and get 2 Hoo, Woo, and Chuckle beans each time! By doing this, you can gain infinite beans and, possibly, infinite stats (Besides 'Stache) from blending these infinite beans.

Here's the game's ending. I hope you'll enjoy it as much as you enjoyed the game: