In addition to its serviceable attack pool and movement speed, Mooth has a repetitive but unorthodox attacking technique where it winds up, rams your cats, and lowers down, all taking a little over a second to execute.
The damage-dealing part of Mooth's one second attack animation is right in the middle, so if new players spam cheap cats that have a quick cooldown period, they will discover that Mooth's pushing power is greatly lowered. This tactic is often referred to by not-so-new players as 'meatshielding,' and will be expanded upon later in Empire of Cats, hint hint.
In the Legend Stages, Mooth's position as a backline enemy is quickly stolen by Owlbrow, an enemy who behaves similarly to Mooth but moves slower and has more attack power in proportion to its health. You'll still be seeing plenty of Mooths in your adventures, because this enemy drops a large amount of money when defeated, and many stages later in the game use Mooths as a money provider.