During every battle, Enemy Units will spawn from the enemy base and attempt to destroy the player's Cat Base. There are currently (version 9.5) over 400 different enemies, each found in different areas of the game.
In addition to stats and abilities, every enemy has at least one trait. An enemy's traits determine which units' abilities will affect it. Traits can usually be distinguished by the enemy's appearance. Some traits also have unique properties.
While every enemy has its own base health and attack power, every level also assigns them a strength magnification (also known as a buff) which further increases or decreases those stats. For example, a Doge at 100% strength magnification has its default stats (90 HP/8 damage) while the same enemy at a 150% buff would have 150% of its base stats (135 HP/12 damage). In Legend Stages, strength magnifications may increase depending on the level's star difficulty.
As of version 9.5, some stages can have enemies whose health and attack power are given separate magnifications. For example, a Doge with 200% HP and 150% attack power would have 100% health than normal but only deal 50% more damage.
Bosses are a special type of enemy found in most levels, usually when the enemy base reaches 99% HP. When a boss spawns, it will produce a "boss shockwave" which knocks back all Cat Units on the battlefield, even those with Knockback Immunity. Bosses also cannot be knocked back behind the enemy base, making it harder to avoid fighting them. The boss is not always the main threat of a level: in many Legend Stages, the boss is merely a peon such as Those Guys or Squire Rel. If the player loses a battle while a boss is alive, the remaining % of the boss's HP will be shown in the game over screen.
List of Enemy Units
Last update: 3/11/2020, cover all enemies in BCJP 9.5.