When using DB's special power Cruel Experiment, if you roll a 6 on a d6, can you use all 3 options during the same turn?

Certainly.

Dear Gaaawd that's nasty!

He doesn't even need to roll for an attack...

Yup. The last line of the card says you can apply all the results. It is a devastating power if it goes off on a 6. I won a few tournies with a well rolled 6. Good luck with him.

You also get to choose he order in which they are applied.

Say R Legacy Joker is on his 4th click with 1 token. You roll a 6.

Deal the plain 1 damage, as he is on his WP click.
Deal the unavoidable damage next, as he is on his Toughness.
Give him the token, as he has no power to stop the push.