Phyrexian Doppelganger

You may have Phyrexian Doppelganger enter the battlefield as a copy of any creature on the battlefield, except all instances of {w} in abilities of that creature are replaced by {p/w}. The same is true for {u} and {p/u}, {b} and {p/b}, {r} and {p/r}, and {g} and {p/g}.
"Both external and internal anatomical features acquire the same phenotype as that of the unsuspecting host. A most incredible being."
-- Politus, Gitaxian morphologist