Pigs seem to make up a majority of the enemy's forces. They can be found just about everywhere. Red pigs are a little smarter than pink pigs. The red ones wander back and forth on whatever platform they occupy, and take care not to fall off. Pink pigs walk right over the edge and keep on walking when they land.
Bird
Mole
These little black birds are commonly found early in the game. They hop along platforms, leaping a short distance up in the air as they go.
Moles only show up in the second stage. They are extremely fond of cake, and like to patrol the small sections of space that they have claimed within. They will leave you alone unless you give them a means to chase you.
Red doll
Flying doll
The large pig boss that you encounter at the end of many stages does not like to fight Upa directly. Instead, they spit out these hopping red dolls to attack you. Inflate them with your rattle and send them flying back at the boss to defeat him.
You'll encounter a few different dolls throughout the game, but these flying dolls are the most common, and the most important. Whenever you are faced with a gap that's too long to jump, these dolls usually appear, and can be struck with your rattle to turn them into floating platforms.
Octopus
Seahorse
You would expect to find an octopus underwater, but many of the octopuses that Upa encounters like to occupy platforms on dry land. They wander back and forth like red pigs.
Unlike octopuses, the seahorses will conform to your expectations and only appear underwater. They seek you out, either dropping down from up above, or chasing after you from below.
Frog
Flying fish
This frog is an extremely rare enemy that you will only really encounter once. It sits still until Upa comes close, and then it hops off in Upa's direction.
Like the flying doll enemy, these flying fishes can come in handy when you're trying to overcome a huge gap. However, they typically fly across the screen quite fast in one sweeping arc.
Kappa
Crab
These water demons known as kappas resemble a cross between a turtle and a penguin. They enjoy sliding across the ice in an effort to catch Upa.
Although they have sharp pincers, the crabs in Upa's kingdom aren't particularly any more dangerous than any other enemy.
Rat
Plug-head snake
Rats find there way inside technology where they enjoy the heat generated by the circuitry. They charge off the end of platforms when they detect intruders.
A special breed of snake inhabits the world inside computers. Their heads look like the end of electrical plugs.
Pencil bomber
Winged bags
Take special care in the fifth world, and watch out for these pencils who come flying by, tossing small explosives at you.
Bags with wings attached to them appear in flocks. When they are just about above Upa, they suddenly stop flying and crash to the ground. Unlike most enemies, they can't be inflated.
Mice
There's nothing mice like more than cheese. And since stage 6-2 is composed entirely of cheese, you can expect to find a lot of mice there. They function a lot like the moles from stage 1-2. Pink mice are restricted to existing spaces while green mice are capable of burrowing their own trails through the cheese, so be careful.
Blue doll
Blue pig
Walking blue dolls won't appear until later in the game. Unlike red dolls, they aren't spit out by a boss, and they don't have wings like the flying dolls.
Like blue dolls, you won't encounter blue pigs until you're closer to the end of the game. Blue pigs are special because they have the ability to hop.
Elephant
Acorn
An enemy that appears late in the game, these elephants use their ears to hover in mid-air while they drop bombs on you. Also appears in green.
A boss pig that rides atop a lightning cloud does not spit red dolls at you. Instead, it spits out these acorns. Aside from appearance, they are the same as red dolls.
Porcu-bomb
Hopping flame
Porcubombs are considerably more dangerous than most enemies. They can't be inflated, and they will explode when Upa gets too close to them.
The hopping flames are another enemy that Upa cannot inflate by striking them with his rattle. They tend to jump higher on every third bounce.
The giant pig is the most common boss throughout the game. He has a particularly large snout, and through this snout, he spits out enemies to attack you. You can turn his attack into his undoing by inflating the enemies that he spits out and sending them flying right back at him.
You'll only encounter the walrus once, at the end of the ice world. At first, he doesn't appear too dangerous, walking constantly in one direction. But after a while, the shoves himself forward on the ice with surprising speed. Get out of his way because he's invulnerable to attack when he does this.
Flame snake
Giant seahorse
The flame spitting snake is one of the few bosses who does not summon other enemies to attack for him. He is more than happy to fry Upa up with his own fire. Despite not creating any enemies, enemies are sure to appear anyway, giving you an opportunity to cool this snake down.
High atop one of the swimming stages, you will reach the den of a very large seahorse who will appear to defend her home. She will summon a group of smaller seahorses to attack you. Naturally, you must turn the tables on her, and send inflated seahorses flying right back at her.
Zai
Little is known about the demon with the goat-like appearance that has managed to escape imprisonment and captured all of the souls in Upa's kingdom. Legend has it that he likes to surround himself with smaller minions who share his appearance. If Upa can get them to break away from following Zai, perhaps he can use them against Zai and restore peace to his kingdom once and for all.
