To me I think it's Shiny Arceus, as Shiny Pokemon are rarer, also could be Shiny Celebi, if it is legit.
The rarest Pokemon ever in my opinion is probably Arceus since it is so hard to get. I like most pies except pineapple or cherry.
the best Pokemon are mewto and the rarest Pokemon ever mew.
Ditto
The rarest Pokemon is a shiny legendary Pokemon holding a really rare item.
The rarest Pokemon is Dialga
there is no rarest Pokemon you have to train and train and including shinies there is no real rarest Pokemon at all.
mew2 is the rarest
No, you do not need cheats to get the rarest Pokemon. The only way to get the rarest Pokemon without cheating is to go to a Nintendo Event, held every few years or so, and download the rarest Pokemon there. Otherwise, you would need cheats to get the rarest Pokemon.
Pikman or Pokemon The Rarest is mewtwo
The rarest is stantler.
zekrom
Pikachu's Illustrator. There are 4 copies in the whole world and worth around 100,000$