Characters

You
You play as the avatar of yourself. This game often breaks the fourth wall by speaking to you as the player or "organic" being, and also speaks of saving the game's world as well as your own real world. You can change your avatar to any that you have unlocked during the course of the game by using your M-Linker and changing it under your Profile.

Pet
This is one of (currently) 3 Micromon that follow you around. Pococo, Beekip, and Crystoise. Each costs 100 diamonds to unlock. Unlocking a pet does not mean it joins your party. They serve no purpose other than to bite your heels while you walk and and make noises at you.

Malk
One of the characters that guides you through the tutorial and communicates with you throughout the game. A scientist, he introduces you to the idea that you are in a digital world and tries to help you get your bearings. To those familiar with the early Pokemon games, he is essentially Professor Oak, since he also gives you choice of your first Micromon.

BOO2
This is a floating robotic ball with five arms that orients you to the game and is found throughout the entire storyline. He is technically the first Micromon you fight and catch, though he isn't in the game for that purpose past the tutorial, and you can't ever use him in your party. In some ways, he is like Claptrap from Borderlands. He and Malk seem to have an interesting relationship but both want you to succeed at whatever quest you are on. He can be found outside every Blue Fox Shop in the towns and if you pay him a small fee, he will teleport you to any of the towns you have previously visited, essentially acting as a paid fast-travel station.