Arceus is also known as "The Original One," as it is said that it created Sinnoh, and possibly the entire Pokémon universe, along with the lake guardians and creation trio. Arceus can only be found in the wild legitimately with the Azure Flute, which has not yet been distributed officially and can currently only be obtained by cheating. However, Arceus itself was distributed via multiple Nintendo events in 2009 and 2010, and distributed via the Pokémon Global Link in 2012.
But technically, it could not have created Pokemon from Gen I - III since it was only exsistant in Gen IV and onward. Therefore Gen V is out of reach too - so technically no. It only created Sinnoh's legendaries for sure.