Adjustable angle climbing wall with electric hoist and pulleys - how to lock the pulleys?
I'd put the winch in the middle, use it only for positioning.

Maybe also have a long length of chain there so that if the winch fails during positioning it can't fall all the way over.  Then again that's a hell of a shock load to your house so it might be better to risk the fall and just stay well clear of it when the winch is moving.

For supporting during use, I'd use unistrut on the two corners. Attach the unistrut via a very heavy duty hinge to the corner of the ceiling and use two captive bolts in the unistrut and L brackets on the climbing wall to hold it tight to the strut.

I laid out some parts to show the idea.


I didn't have a large hinge so I used black plastic pieces.  You should be thinking large barn door hinge though.

The two 1" pieces represent your ceiling and basement wall.  The 2" lumber is your climbing wall.

Be careful of how long the strut is so it doesn't stick out and become a hazard.  Against a wall wouldn't matter, but in the middle of the room you could walk into it potentially.

Unistrut can handle loads of many thousands of pounds and obviously holds in tension and compression.  You'd use a wrench from the climbing side to loosen the bolt heads to allow the winch to move it, then tighten back up before climbing.

The wood screws in this example might not be able to be inserted all the way because I doubt that angle will be 90 all the time.

Climb on!