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There are a variety of enemies that move about in different patterns. Contact with an enemy (or the missiles fired by some) will kill a dragon. The dragons' job is to complete the level by killing all enemies in it. If this is not achieved within a time limit, the message "Hurry up!" will flash across the screen. When this happens, enemies become "angry" (making them red and move faster thus making them more dangerous). Approximately ten seconds later, one or two Skel enemies appear on screen. Enemies also become "angry" if they escape from a bubble that is not burst quickly enough by one of the dragons. They may but not always calm down when one of the dragons dies. When in Super Mode, most enemies get swapped with a counterpart, e.g. PulPuls replace Monstas and viceversa.

There are 8 kinds of normal enemies, plus the final boss and two kinds of invincible monsters that appear after the "Hurry up!" limit, each with their own names. Roughly, in order of appearance in the Normal version of the game, they are:

• Bubble Buster (Japanese "Zen-Chan") (Bonzo in Europe): A box-shaped, clockwork walking monster with a medium moving speed and good jumping abilities. He's the first monster that appears in the game at stage 1. Interestingly, this monster also appears in the graphic tiles of the ROM of the arcade game Chack'n Pop, along with the Stoner and Beluga, but doesn't actually appear inside the game. Super Mode counterpart: Incendo.
• Stoner (Japanese "Mighta") (Boris in Europe): A walking monster with red eyes who wears a white robe, much like a ghost. Has a medium moving speed, good jumping abilities and is able to shoot. First appearing in this game at stage 6, this monster actually first appeared in Taito's 1983 game Chack'n Pop. Super Mode counterpart: Willy Whistle.
• Beluga (Japanese "Monsta") (Blubba in Europe): A flying blue/dark purple monster shaped roughly like a small whale. It flies fast but can only bounce off walls to change direction. First appearing in this game at stage 10, this monster actually first appeared in Chack'n Pop. Super Mode counterpart: Hullaballoon.
• Hullaballoon (Japanese "Pulpul") (Boa Boa in Europe): A pink flying monster looking like a toy bear with a small rotor on his head. Flies around slowly but with greater control than the Beluga, and creeps in very small openings that other monsters and players cannot pass through, thus making it very dangerous in some rounds. It makes its debut at stage 20. (Super Mode counterpart of Beluga)
• Coiley (Japanese "Banebou") (Bonnie-bo in Europe): A mushroom shaped-monster which can only move by making short jumps, having a single powerful spring instead of legs. It makes its first appearance at stage 30, and is the only monster who stays the same in Super Mode (he is not swapped with any other monster).
• Incendo (Japanese "Hidegons", singular): A fast walking monster with shooting abilities, but poor jumping. Unlike the Stoner, he doesn't have to stop walking in order to shoot fireballs. He makes his first appearance at stage 40. (Super Mode counterpart of Bubble Buster)
• Willy Whistle (Japanese "Drunk") (Bonner in Europe): A fast moving monster with good jumping capabilities, and able to throw a bottle which rebounds off walls and is re-caught by the thrower. He first appears at stage 50. The final boss is modeled after them, but is instead called Grumple Gromit or Super Drunk. (Super Mode counterpart of Stoner)
• Super Socket (Japanese "Invader"): A robotic-looking monster, which behaves similarly to the enemies from the computer game, Space Invaders. Can only move left or right, and falls if it reaches the end of a platform. Shoots lasers downwards. It first appears at stage 60, but does not appear at all in the Super version of the game. (Incendo takes its place in Super Mode.)
• Baron von Blubba (Japanese "Skel-Monsta"): It is the invincible monster that appears after the time limit for a round has expired (this limit can be as low as 1 or 2 seconds on some rounds, but there are two rounds with no time limit: round 94 and round 100). It looks similar to a white Monsta, but can only move vertically or horizontally at timed intervals. It can pass through walls, ceilings and floors, and speeds up until either the level is completed or a player is killed. In two-player mode, two Skels appear, each homing in on a particular player, although either player can be killed by touching either of the Skels. A Skel can also be dismissed by touching a player who has just been killed and is still flickering, and thus invincible. Another way to get rid of Skel is to pick up the flashing heart powerup (the only one which remains on the screen after the "Hurry up!" warning.
• Rubblen (Japanese "Rascal") appears in the secret diamond-filled rounds, which can be accessed by special bonuses that appear on rounds 20, 30 and 40 under certain conditions (explained in later section). Losing one's last life inside such a secret room will cause the maximum round reached to be "Round 102", "Round 103" or "Round 104" depending upon in which secret room death occurred, and the first new game started after that will teleport players to the first secret round straight from round 1, but will also cause secret rounds to appear earlier, at stages 10, 20 and 30, and the special 20-stage skip bonus on stage 40 instead of stage 50.
• Grumple Gromit (Japanese "Super Drunk") is the end-game boss that appears in level 100. It is large, bounces off walls, and fires arcs of bottles. The level contains a magic potion that allows the players to breathe lightning bubbles. It becomes trapped in a bubble only after being struck by many lightning bolts.