It's a complicated situation. It blocks some, but not all priority associated with Prankster.
Say I've got a Sableye up against a Tapu Lele (ahaha, what a wonderful concept). If I have Prankster, my Sableye could use Toxic or Will-O-Wisp on Lele, but it would fail because of the Terrain. However, I could get away with using something like Recover or Calm Mind with advanced priority because it doesn't target the opponent.
Based on this, Comfey cannot use a Triage Draining Kiss, nor can Talonflame use Gale Wings Flying moves, like Brave Bird.
These moves would not be blocked by Prankster in Psychic Terrain, except for Perish Song, Flower Shield, and Rototiller. Note that it's impossible to have some of these moves on a Pokemon that gets Prankster.
For more info, see Psychic Terrain's Bulbapedia page.