Mew

{r/g}{b/r}{u/b}: Mew becomes a copy of target creature
and gains this ability.
{g/w}{w/u}: Exile Mew. Return it to the battlefield at
the beginning of the next End Phase.
It is said to possess the genes of all Pokemon. It is
capable of making itself invisible at will, so it entirely
avoids notice even if it approaches people.
-Pokedex entry