The monstahs are a species of violent creatures. They can take many forms, but are always evil, and always have a lion's head. Nobody has survived an attack from a monstah, though Chuck Norris is rumored to have shot one at one point. The monstahs are the most dangerous creatures in Loompaland.
There are several koopas that have been abandoned in Loompaland. This is because Bowser was searching for treasure in Loompaland, and when he was done, he forgot to bring the koopas with him. They eventually became vicious flesh-eating killers.
Fluguy is a Pokemon that lives deep in the forests of Loompaland. Due to not being trained like most of those uglies are, they have become particularly vicious, even for Pokemon. They are also very sick, and have trouble attacking because they need to cough and/or sneeze.
Loompaland has one of the highest monkey creature populations in the entire world. It even has more monkey creatures than the Zoo! And they have LOTS of monkey creatures there. It is believed that the monkey creatures found in Loompaland are a subspecies called Loompa Monkey Creatures, but the only person who's ever tried to confirm this was Patrick Star, and he failed miserably.
The Oompa Loompas, as pathetic and harmless as they are, are technically Loompaland monsters. Before they were kidnapped by Willy Wonka, they were actually kind of tough. They were bouncy enough to kill people, and they could shoot Energy Blasts at will. But then he took them, and they lost their powers. They now have the power to Blow Stuff Up.