The Hunger Games
Golden Dart Frog
This is a Poison dart frog, plain and simple
A cow like animal that can charge and often kill at amazing rates
This kitten has razor sharp wire on its back coated with hallucinogens that can sometimes cause death. The wire is embedded in the back of the kitten so when you pet it you get the hallucinogens
The Cornucopia would contain warm-weather clothing as the tributes are sent out in only a winter parka, and cat food. The Cornucopia would be in the middle of the trifecta of ecosystems.
The Frog is in the Rainforest, The Buffalo is in the Grassland, and the Kitten is in the Desert.
The rainforest is moist but covered. The desert is out in the open and clear, but very hot. The grassland has the Buffalo which can see very far, but has no extreme temperatures.
The relationship with the contestants is they die. Thats it. Nothing else. Just. Death.