What happens when Whimsicott uses trick room?

Question

So, I noticed that Whimsicott can learn trick room, and I also noticed it's popular ability, prankster, that gives all non-attacking moves a priority of +1.
Since trick room has a priority of -7, will prankster set it's priority to +1 or -6?

Answer 1

>If a Pokemon with Prankster uses Trick Room, it has a priority of -6.

Smogon - Trick Room