Pokemon Sun and Pokemon Moon feature a rare type of Pokemon called Cosmog. You can find out details on how to capture it from here. Keep in mind that this rare Cosmog can only be found once per each copy of the game, which means there is no way to get another Cosmog in the game unless you opt for cheats.
Each Pokemon generation and entry brings up something new to the franchise. Let's talk about the rankings of every Pokemon generation.
NE: "We go over 10 of the hardest Shiny Pokemon to catch across every generation of Pokemon."
Even if the eShop has now closed down, the best 3DS games are still worth playing — in any way you can get your hands on them.