TMP - Age up Anakin to about 17/18.
AOTC - Give Obi-Wan another pupil, who is also tempted towards the dark side.
ROTS - Make it look like Anakin and the other pupil die about midway through the movie, with proto-Vader (mask, but no life support suit) taking his place.
YES to all of these, though I don’t think “no life support suit” is necessary for act 3 EpIII Vader.