on Earth, genetic engineering on four bear cubs gives them human-level intelligence and psionic powers of the mind, including teleportation, levitation, telekinesis, and the ability to create illusions. However, they soon turn to evil. They call themselves Pain Bear, Fear Bear, Doom Bear, and Nightmare Bear. Pain Bear has a tattoo on his belly with a human skull with thorny plant stalks sticking out. Fear Bear has on his belly a tattoo with a booing ghost rising out of a human skull. Doom Bear has on his belly tattoo an atomic mushroom cloud rising out of a skull. Nightmare Bear on his belly tattoo has a werewolf/demon hybrid rising out of a skull. Not unlike the cutie marks of Equestrian ponies!
They then use their powers of the mind to teleport to Equestria, and pretty soon they use their teleportation and levitation powers to move rapidly, use their powers to create illusions in order to torture ponies with images of flames and monsters, and telekinesis to steal from ponies.
Or Fluttershy, being ignorant of the Terror Bears' human-level intelligence and psionic powers, may attempt to use her skill with animals on them.
Source for the Terror Bears: turtlepedia.wikia.com/wiki/Terror_Bears