The only CharacterState actually referenced by the core Character component is their Idle state because that's the default state they start in (if an Introduction State doesn't start itself instead) and return to after completing other actions so every Character needs one. All other states are either self-contained (like the Introduction state) or controlled by other scripts (such as the Brains which directly reference the actions they can perform).

The IdleState causes the character to simply play an animation while stationary, but the Character.Idle field actually allows any type of CharacterState to be assigned so that the Idle Character State means "able to move and act freely" rather than specifically "standing still".

State Class Used By Description
Idle IdleState Maw Flower Plays a single animation and doesn't allow movement.
Mobile Idle MobileIdleState Gobbat Plays a single animation like Idle, but also allows movement.
Locomotion LocomotionState Player, Gobbler, Naga, Scarecrow Plays an Idle, Walk, Run, or Fall animation and allows movement.
Wall Slide WallSlideState Player Slows the character's falling by grabbing a wall.
Land LandState Player An extra animation used when the character lands on a platform.
Multi State MultiState Player A "state selector" which simply picks from a list of other states. This is the state assigned as the Player's actual Character.Idle.