Dimonix

Dimonix, also known as Diminox, Dimondox, Dmonix and Dimanonix, is a PokéGod. It was thought to be the evolved form of Onix.

Origin
Like many other Pokémon, Onix was thought to have another evolution. This led to the creation of Dimonix. Dimonix is a PokéGod (which means it was purely a fan concept.) Most artwork seem to reflect that Dimonix is made out of volcanic rock. There was a bit more information on Dimonix's appearance: it was said to have horns at first, but later codes described wings as well. This may have been based on the name "Dmonix," which sounds similar to "Demonics," which contains the word demon, leading to it having the demonic features of horns and wings.

Steelix is not a significant Pokèmon because Onix was not a popular Pokémon, like many of the other pre-evolutions to PokéGods were. This leads to a possible origin of the Crystal Onix, which was mistaken for proof of Dimonix.. it being from the anime, who could easily have been mistaken as being made of diamond.

Mist Stone
The mainly circulated way to obtain a Dimonix was through the use of a Mist Stone.

Trade
The other major code to get the Dimonix was to trade an Onix level 60 multiple times. Occasionally, this would have to be for another Onix level 60. The amount of times was usually four or six, but could go even higher. This code shares similarities with the true evolution of Onix into Steelix as both involve trading.