Nobody:
Blake: So you're going to fit four people on a wheel chair, roll it down a mountain into a horde of zombies and jump it over a 60ft wall using a tree as a bounce pad.
Episode 6 Praxeus.
Oh boy this ones my favorite
It seriously fixed the problems with the companions by literally spreading them out within the entire planet. It felt like a classic DW adventure. It also had a somewhat subtle message about plastic pollution. It was very good.
Like none of the companions are doing a bad job. It's just they don't do anything. Like yeah companions are supposed to be somewhat clueless to compare the Doctors intelligence to a regular human, but these guys take it to a while new level.
What if sometimes characters couldn't make it to the adventure. Yaz still has a family and a job, so what if it was like a duo or trio episode. Also Ryan needs to stop being a clueless idiot, make him more clever. Or do a Rory Amy thing with Ryan and Yaz.