Because Arceus created the universe and then became a pokemon. But what about the other legendaries that created shit? I don't know same thing I guess.
Arceus>Creaton Trio>Lake Trio>Mew>Weather Trio and Regi Quartet>Fossil Pokemon>Humans, Almost every other pokemon>Legendary Beasts and Muskedeers>Porygon Line, Mewtwo, Ditto, Genesect
Mew is not the first pokemon, he/she is the Ancestor of all pokemon, there's a diference between being the first and being the ancestor. Also Arceus created all the Pokeverse and then assigned a specific realm/dimension to a certain pokemon, like Dialga ruling Time and Palkia ruling Space.
Mew isn't the first Pokemon. It may be the ancestor of all Pokemon, but that doesn't mean it was the first.
@Norzan; @Team Gaara; How can you birth things that existed before you unless time travel.
@Phoenixphlare; The appearance of the egg with Arceus can be seen as the same as the Big Bang of our Universe, nothing existed until Arceus was born and when he created Dialga and Palkia Time and Space started to move.
@Norzan; Wait was this confirmed? And this doesn't answer the question.
technically speaking rhydon is the first pokemon xD
People have been asking this question ever since DP. I don't think they really thought this through very well.
Obviously Mew existed before the universe.
Mew being the ancestor of all Pokemon doesn't even make much sense since they don't even know all the pokemon out there.
@Phoenixphlare; Platinum entry "It is said to have emerged from an egg in a place where there was nothing, then shaped the world.", NOTHING existed before Arceus, it was Arceus that created all. And yes i answered your question, you asked how can you give birth to things that existed before you but nothing existed before Arceus, Arceus created the entire Pokeverse.
@Norzan; 1. I don't take the pokedex seriously for many reasons. 2. "It is said" 3. That didn't answer the question all you said was Arceus was first. If want to say you reject Mew being all pokemon's Ancestor say it but don't act like you found a solution when you didn't. If Arceus is a pokemon and Mew is ansestor of all pokemon then the Mew had to have birth Arceus or his ancestors. 4. That dex entry doesn't even conflict with my theory. It could hatch from the egg as a non pokemon created the universe and then began a pokemon through going into a descendant of Mew.
I don't understand your question. Arceus was first. Mew came after it. Neither birthed the other.
There was absolutely no 'BOOM HEADSHOT' moment within that comment.
Your actual question can be answered simply by correcting the major mistake in your original question - there is a difference between being the 'first' and being the 'ancestor to all.' Yes, the dex entry confuses matters somewhat but common sense allows us to assume that Mew is ancestor to all non-legendary Pokemon.
The word 'legendary' is vital here. None of these Pokemon - Arceus, Mew, Palkia, Dalgia etc. - are technically PROVEN to exist. They are stuff of legend.
So really the whole topic is completely open to individual interpretation.