This level had the potential of 6 stars but the momentum move was inconsistent and became annoying. On my 1st attempt to drop the ZapperR release ball, B needed about 10 attempts to nudge the ball but then I realized that it would be best to release Z later but that wasn't possible as B needed so many attempts for the momentum moves, the ball always fell before I wanted it.
I'm lost--I can't get very far on this level. Am I missing something, or is something broken? Is B supposed to be able to mount R? Because B cannot. I can't get B down or do anything interesting with R or Z. Are there unstated tricks? I can Spoiler get out B out of the opening area by raising the shadowed slider. I can use autopilot to get B on the jagged stock block section on top and stand pointlessly on Z's head. But that's about it.
After multiple attempts, I was able to squeeze B down a level with the elevator draggable, which opened up more possibilities.
Miracle of miracles -- I beat the level and got it on video. My solution makes @ridgerunner 's "some awkward moves" comment look like an understatement, so I'd be very interested to know if there were stabler solutions. So, I am simultaneously proud (because solving it really stretched my abilities) and not proud (because it's really not pretty!) of this solution. Spoiler: Video Solution
Well done! I didn't know about the move that Spoiler uses the draggable to squeeze B up a level. And maybe I can improve my SBS technique!