Chenook = Frankie Black (Freddie cypher)
Psycho = Roberta Blockly (Velma cypher)
Aero = Amelia Hairhart (Daphne cypher)
Mr Mystery = The Mystery-Moblile (Mystery Machine cypher)
In addition there was:
Norville "Sketchy" McDraw (Shaggy cypher)
Zeusie Zoo (Scooby cypher).
2) JOKE arrived in a Kaiju-based universe where they battled giant monster versions of their enemies sent to earth by Planet Z. In this universe:
Chenook was a giant version of the pre-2000 Chenook (i.e. he had a tail)
Mr Mystery was a Jet Jaguar type robot.
Aero was a giant Cousin It type monster.
Psycho was... wait I've forgotten. It breathed lightning anyway.
The final monster was King Zeus (3 headed sound blasting dragon).
3) They arrived in a Planet of The Apes universe. Here JOKE were still alive. They were:
They also met astronaut Hubert Heston, a human version of Chief Inspector Chimp, who had time travelled via spacecraft from 1963. (The trip that created The Invaders in JOKE's universe).
Sent to kill this world's JOKE were a pre-2000 incarnation of The Eight, namely the version led by Professor Awful. Apparantly this was the Professor Awful from the pre-2000 timeline who had been plucked from the timestream by the mysterious individual(s) who are killing all the JOKEs off. (he had been put there by Animator).
4) Leaving the Ape world with Hubert in tow (now with Mind Control powers from Mr Mystery's radiation), they found themselves on a world were JOKE are feared as villains...