How did Gamzee get Lil Cal into Dave's dream room? I know he used chucklevoodoos but since Cal's supposed to be a juju, it wouldn't make sense for Gam just to have made him out of thin air

My guess is that the Gamzee inside Cal used some chuckle voodoo shit to get in Dave’s dreams since Gamzee in the past but also the future knew that he would cause Cal to get there.  Confusing, I know. So many things about Cal were caused by a different part of Cal, paradoxes are hard to explain.