Hint Toad

Blue Toad is one of the five members of the Toad Brigade, who acts as Princess Peach's attendants and royal guards. He is the smartest member of the brigade and often helps Mario with the use of his knowledge.

Super Mario Galaxy
In this game, Blue Toad appears as one of the five members in the Toad Brigade. Eventually, Mario comes along and saves the five Toads (including Blue Toad) in the Honeyhive Galaxy. Throughout the game, the Toad Brigade attempts to help Mario on his quest by traveling throughout the different galaxies in the search for Power Stars. In their last game appearance, the five Toads are revealed to have been promoted to Royal Guards due to their work of helping Mario.

Of the Toad Brigade, Blue Toad is shown to be the smartest of the five Toads and has provided Mario with some very useful information about the galaxies. To show his intelligence, Blue Toad appears wearing glasses in this game and is called the "smart one".

Super Mario Galaxy 2
Blue Toad is once again part of the Toad Brigade in Super Mario Galaxy 2. He, along with the other Toads in the brigade, arrives on Starship Mario after Mario clears Spin-Dig Galaxy. Once again, he is the smartest, and often gives Mario hints on how to defeat Bowser. His speech changes every time Mario clears a world.

Captain Toad: Treasure Tacker
Blue Toad appears in Captain Toad: Treasure Tracker. He appears in some levels and will give the player a Diamond when the player finds him.

Trivia

 * Blue Toad shares many similar characteristics and looks similar to the characters Toadbert and Russ T. as they are all blue-spotted Toads, are intelligent, and wear glasses.
 * In Super Mario Galaxy 2, after giving the Banktoad 1000 Star Bits, he will wear a pair of glasses similar to Blue Toad's pair because he wants to look smart.
 * In Super Mario Galaxy 2 in Boulder Bowl Galaxy, the Blue Toad will be picking at the ground with a pickaxe. He says he lost his glasses, but upon closer examination using the first-person view, he is actually hitting his glasses with his pick.