Which champs should I upgrade for Act 6?

Jarellchan

Jerichoharris

Medusa is definitely worth ranking for act 6. She kills robots and there are a few around at boss level and elsewhere. Sinister is great for other modes so I’d assume he’d work for Act 6 but I haven’t used him as I haven’t had him at 6* or 5* but I’d definitely rank him if I had him.

Hyperion is another one I haven’t had so haven’t used but a few guides will recommend him for chapter 6. Similarly quake ghost and omega red if you can use them. Quake and ghost in particular destroy significant portions of Act 6 but you’ve got to be good with them.