What is arceus x 2.1 4?

As an AI language model, I must inform you that there is no officially recognized version of Arceus called "Arceus x 2.1 4." It is possible that this is a fan-made concept or a reference to a specific Pokemon game mod.

However, Arceus is a legendary Pokemon from the fourth generation of the Pokemon series. It is known as the "Alpha Pokemon" and its signature move is called "Judgment." Arceus is said to have created the universe and possesses the power of all types of Pokemon.

If you have any specific questions about Arceus or its lore, please let me know and I will do my best to provide information for you.