N_Jellyfish
One day, there was a chemical spill in the ocean. The spill took a while to clean up, but it affected the various jellyfish in the area, giving them new abilities and powers. Now they've arrived in the park. Only time will tell what'll happen now.
The jellyfish look exactly like normal jellyfish except that they flash in various colors. How fast and bright the colors are that they flash in is dertermined by their power. The more powerful the jellyfish, the faster and brighter the colors shine.
The jellyfish feed by draining the energy of other creatures and draining energy from anything that has it. Jellyfish captains and generals have even been known to eat weakened prey whole once the prey's energy is gone.
There is more than one kind of jellyfish too.
Kinds of jellyfish
Grunts: These survive on pure instinct and are the least dangerous type of jellyfish due to their small size and low power. A large enough group of these can be dangerous though. They're the most common type of jellyfish as well as the smallest, almost never being more than a foot in diameter, and usually form groups of 50-100 grunts.
Captains: These are a bit smarter than grunts and will work together with other captains to catch pesky prey. They tend to avoid metal and will try dodging if attacked by metal. They're not as common as grunts, but more common than generals, and generally form groups of 10-20 captains and average 2-3 feet in diameter.
Generals: The most dangerous type. They're generally alone, and are 5 feet in diameter. They are very smart for jellyfish, and are sentient with the ability to think.
Kings: Even rarer than generals, they're 20 feet across generally, and newly discovered. They're smarter than generals too, having the intellect equivalent of a 9 year old human child. That, combined with their ability to talk makes them not as dangerous as generals since they can be reasoned with.
Abilities
Flight: The jellyfish can float through the air as if it was water.
Energy absorb: The jellyfish absorb any and all energy attacks. If they absorb too much energy though, they could end up exploding.
Acidic blood: The blood of the jellyfish is acidic, and will eat right through most things it touches. The blood only leaks out when one of them dies though, and this makes eating one fatal for any pred that tries.
Weaknesses
Metal: Metal objects are like acid to them. If one of them touches anything metal, they quickly lose energyand grow weaker, eventually dying if the metal object isn't removed.
Limited intelligence: The jellyfish aren't very smart, and most survive on instinct.
Strengths
Sheer numbers: There are literally millions of them.