Toad Brigade

The Toad Brigade is a group of five Toads that aid Mario in Super Mario Galaxy. It seems likely they are the same Toads who first accompanied Mario and Princess Peach to Isle Delfino in Super Mario Sunshine, where they had minor roles and no individual personalities. At this point in time, though, they had not formed the Toad Brigade.

Three of those Toads had also appeared in Mario vs. Donkey Kong, as assistants in the production of Mini-Mario toys. There is also a possibility that they are the five playable Toads in Mario Superstar Baseball and Mario Super Sluggers.

Super Mario Galaxy
Enjoying the festivities in Peach's Castle during the Star Festival, Toad and the Toad Brigade were scattered across the galaxy after Bowser carried his castle into outer space. They eventually escaped, along with Luigi, until they were separated from him and were later discovered by Mario in the Honeyhive Galaxy, where he rescued them.

Shortly afterwards, the Toads join Mario at the Comet Observatory, where they decide to help him in his quest to gather the Grand Stars, and move their base of operations to the Garage. After the Lumas help them build a spaceship, the Starshroom, the Toads form the Toad Brigade and start traveling in order to find Power Stars with Mario. They are then seen throughout several galaxies in search for the stars, and often cheer Mario on during battles. They often arrive to provide a Launch Star to Mario on their ship in order to help him progress.

The five members of the Toad Brigade each have special attributes: the leader is Toad who, despite trying to come off as brave is always fleeing at the first sight of trouble, making up ridiculous excuses along the way. He can be seen as rather lazy. The Purple Toad is the Mailtoad. He will give Mario letters from Peach or Luigi when received. He also enjoys snorkeling, and can often be found underwater or with a snorkel mask. The Blue Toad wears glasses, and often gives Mario advice in levels. The Green Toad, Banktoad carries a pickaxe, and often sings songs while digging with it. The Yellow Toad is very lazy, and is either sleeping, much to the annoyance of a yellow Luma, or spinning around in circles.

In the Grand Finale Galaxy they show up for a final time. Their leader reveals that because of their work in helping Mario retrieve the stars, they have been promoted to Royal Guards.

Super Mario Galaxy 2
The Toad Brigade does appear in Super Mario Galaxy 2. Like in the prequel, they continue to aid Mario throughout the different worlds.

Being that the game plays in a way that makes the the story of Super Mario Galaxy to appear to not exist, much of the background behind the Toad Brigade is introduced in this game. Firstly, Toad has the other toads refer to him as "the new captain" and, when he is first met, he reveals he is actually Toad who instated himself as captain simply by wearing a headlamp. Additionally, the Brigade does not seem to know as much about the Lumas as they did before. The Starshroom used in Super Mario Galaxy 2 was stated by brigade members who reveals that the Lumas built it for them so they could return to follow Mario to help him on his quest. Also, they do not talk about their previous exploits and some have different roles in comparison to the original game. For example, the Green Toad now is a Banktoad and not an adventurer as he was in the previous game. The Mailtoad continues to give Mario letters. Additionally, Mario can give the Banktoad some of his Star Bits.

Throughout the game, the Toad Brigade follows the Starship Mario using their starshroom. Mario can go onto to their starshroom simply by using a teleportation pad on the Starship Mario in order to speak with them. They sometimes assist him on his journey but generally they are just seen exploring the areas rather than looking for power stars. In the Bowser levels, the Toads are sometimes seen deep within the area, with the Toads often having a coin for Mario to collect. In the ending, the Toads are seen celebrating within the credits as Mario finally gets the cake that he had earned from saving Princess Peach.

Trivia

 * The Toad Brigade Captain is believed to be the character Toad as seen by their similar personalities, both being red-capped toads and the fact that Toad had artwork provided for Super Mario Galaxy. He is even referred to as Toad in his Super Mario Galaxy trading card, name and bio-wise.
 * Like Mailtoad, Banktoad wasn't given a name or a real occupation until a Super Mario Galaxy game, with Super Mario Galaxy 2 being the one for Banktoad.