Meta Battle Subway PokeBase - Pokemon Q&A  If Mewtwo is the
Clone of Mew, why is it before Mew in the Pokedex ?  1 vote
asked Feb 7, 2013 by MK 42  3 Answers  2 votes Best answer  The
reason is that mew was originally supposed to be a secret, even
unknown to many people in nintendo. So to keep it a secret they
had it last in the pokedex. It wouldnt be a secret if there was
a space in the pokedex going from 149(dragonite) to a space(mew)
to 151 (mewtwo). So they did it to hide mew's existence until it
was revealed and released as an event. Another reason is that
mew is event exclusive and all event exclusive Pokemon come last
in the pokedex for their respective generation with the
exception of vicitni.  answered Feb 7, 2013 by CWegz edited Feb
7, 2013 by CWegz 1 vote  The pokedex was just designed this way.
They were both introduced in Gen I and the order does not always
have to be perfect. Otherwise Arceus should be #001 in the
pokedex.  answered Feb 7, 2013 by DracoArceus yes, but Arceus is
a Sinnoh pokemon