Blowfish Transporter
Turtloid
Small Monsters
Medium Monsters
Boss Monsters
Blowfish Transporter
Turtloid
Super Boss Monsters
Special Monsters
Green World
Desert World
Green Hill Zone exclusives
Royal World
Beach World
Ice World
Lava World
Spooky World
Arcade World
Battle Mods Exclusive
Summary
Monsters are creatures you can find all over the map. Busting them will give you some loot to help building your Squad. They are the primary source of coins in a battle, using which you will get more characters to your squad.
Monster Types
Small Monsters
Small Monsters is the most common kind of monsters, and they are... small. These ones don't have an incredible health, damage, or even loot. They are mostly here to help you build your Squad at the beginning of the game.
Medium Monsters
Medium Monsters can be identified by a slightly larger health bar. Neither are they weak, nor are they strong. These monsters are in the middle. They have decent loot, enough to help you build enough Coins for a new Chest.
Boss Monsters
Boss Monsters are tankier and stronger than Normal Monsters, and give much more loot. Boss Monsters also get special attacks, like how the 
Baby Dragon can shoot fireballs. There is also a stat on your profile, showing how many Boss Monsters you have busted. In-battle, there is also a Boss Monster icon next to Boss Monsters' gigantic health bars.
Super Boss Monsters
These Monsters are the strongest, the tankiest of them all, and have crazy loot if you manage to bust them! While you are struggling to burn through that colossal HP, other players may will try to backstab you, so watch out! These Super Boss Monsters only spawn in the center of the map. Just like the Boss Monsters, there is a separate stat on your profile for tracking how many Super Boss Monsters you have busted. In-battle, there is also a Super Boss Monster icon next to Super Boss Monsters' gigantic health bars, just like the Boss Monsters. There can only be one same Super Boss Monster on the map at the same time (except for 
Tree Giants). Some even replace the Gem Mine!
Special Monsters
Some Battle Mods Exclusive Monsters have something really unique from all the other Monsters in the game. They can change type and stats. Only 2 Special Monsters exist: 
Gift Critters and 
Chest Imposters. The Gift Critter spawns everywhere in the map, and depending on where it spawns, it can become a Small Monster, a Medium Monster, or even a Boss Monster. Same attacks, but its stats greatly change. The Chest Imposter gets different stats depending on the Chest rarity beforehand, but doesn't change its Monster type. Note that this type name is not official, and doesn't come from the game's files, with the Gift Critters being considered Small Monsters and Chest Imposters being considered Medium Monsters internally.
Trivia
- Boss Monsters are sometimes mistaken to be called 'Big Monsters', and Super Boss Monsters as 'Boss Monsters'.
- In every World, there seems to always be at least one melee Small Monster, one ranged Small Monster, one melee Medium Monster... If you understand the pattern, you could try to guess the new Worlds' Monsters.
- Challenges that require busting Boss Monsters is inclusive of both Boss and Super Boss Monsters.