The caffeinated pokemon: The internal temperature of the liquid that makes up this pokemons body is constantly just above freezing point, allowing it to harden it into a solid in a flash for attacking or defending. Nitroxius is known to be extremely hyper even when asleep, however the hyperactivity is slowed when asleep.
If your wondering why a ENERGY DRINK is Poison/Ice and not something like Electric is simple: Ive seen various energy drink based pokemon that are electric so wanted something more unique. Also all energy drink brands have a warning label on the can or bottle saying that its not recommended for some people to drink and large doses of caffeine can be deadly (hints the poison type), as for the ice type, who drinks room temperature energy drinks??
The name Nitroxius came from both Nitrous and Noxious. Nitrous is used in cars with a Nitrous Oxide System (or NOS) to increased horsepower and speed, and lots of media tend to show caffeine and sugar causing people, especially little kids, to get hyper and run around fast (plus there is a energy drink brand named Nos) while Noxious means harmful or poisonous
by UnNamed_Profile27