Arceist: The radical group that believes Arceus proclamation that it wished not to be worshiped was a test and have chosen to bring Arceus glory all around the world. Based out of the cathedral Hearthome city in Sinnoh. While only a percentage of believers are so radical as to preform demonstrations most would agree with them.
Main goal is to unite the world under one religion of the true creator and end all strife.

Rayquaza cult: Came into being as a reaction to Arceus existence, fearing the fact that a creator could easily destroy everything they wish to awaken Rayquaza along with Groudon and Kyogre to defeat Arceus. Very few numbers at the moment but they are quickly gaining power in Hoenn
Main goal to kill a god

Another group of people who respect and fear the power of the legendaries aim to save humans by creating their own super powerful pokemon to fight the gods.