  We present exact dynamical and inhomogeneous solutions in three-dimensional
AdS gravity with a conformally coupled scalar field. They contain stealth
configurations of the scalar field overflying the BTZ spacetime and also
solutions with a non-vanishing energy-momentum tensor. The latter non-stealth
class consists of the solution obtained by Xu and its analytic extension. It is
shown that this proper extension represents: (i) an eternally shrinking
dynamical black hole, (ii) a curious spacetime which admits an event horizon
without any trapped surface, or (iii) gravitational collapse of a scalar field
in an asymptotically AdS spacetime. In the last case, by attaching the solution
regularly to the past massless BTZ spacetime with a vanishing scalar field, the
whole spacetime represents the black-hole formation from regular initial data
in an asymptotically AdS spacetime. Depending on the parameters, the formed
black hole can be asymptotically static in far future.
