Mercurial Pretender copies exactly what was printed on the original creature and nothing more (unless that creature is copying something else or is a token; see below). It doesn’t copy whether that creature is tapped or untapped, whether it has any counters on it or Auras attached to it, or any non-copy effects that have changed its power, toughness, types, color, etc. For example, if Mercurial Pretender enters the battlefield as a copy of a Profane Memento with Ensoul Artifact attached to it, Mercurial Pretender will be a noncreature Profane Memento with Mercurial Pretender’s added activated ability.