revisiting my opinions on which doctors could pull off Heaven Sent
could do it with minimal alterations to the original episode's plot and dialogue
Eight - could 100% pull off the speeches and the angst and, of course, the memory loss. The episode would definitely be focused a little more on the great tragedy of dying over and over and over again just in the hopes of making it through enough loops to break out, and Eight would be much much more of a sad wet cat about it all, but he could totally pull it off.
Seven - would take a bit more tweaking than Eight (specifically to change the focus of the episode to the puzzle of it all, finding the right room and figuring out the secret of the Veil), but would 100% punch his way through the wall and be able to pull off the speeches.
could maybe do it? but with pretty major edits
Four - definitely has the charisma and the ability to give the speeches, but I don't know if the speeches as written would fit well into how Four talks, and he'd also need the same tweaking at Seven to make it more about solving the mystery, rather than the very atmospheric style of the original. The wall scene would also probably have to be reworked, since Four doesn't really seem like the type to punch through it in the exact same way as Twelve.
Three - could and would punch through the wall and would do it in half the time of Twelve but couldn't carry off the angst or the atmosphere, so you'd need some pretty dramatic rejiggering of the major stylistic choices in order to make it work. Honestly, you might have to really lean into a, like, horror/thriller kinda thing, with the pursuit of the Veil?
could pull off a focus episode but would need a fundamentally different style
Ten/Fourteen - absolutely has the screen presence but they need someone to talk to in order to get it, and the same is true of their problem-solving style. They need someone to bounce off of as an antagonist and as a companion -- basically, they need the same setup as Wild Blue Yonder, which is basically exactly what Fourteen's version of Heaven Sent would be anyways. (Also Ten doesn't do speeches like Twelve does, and definitely wouldn't punch through the wall -- his problem-solving style leans more towards the whole "push a single button that sets off a chain reaction that solves everything" rather than sheer stubborness. He doesn't have the attention span for the wall.)
Nine - Nine also has the screen presence but his comes when he's angry at something, which means that he needs something to yell at, so he would also need another speaking being present in the episode for him to get really really mad at. Think Dalek but without the Rose subplots?
probably not
(note: the major reason why none of these work for Heaven Sent is because they're all Doctors that work best with an ensemble cast around them -- they sacrifice intensity and screen-presence for the sake of letting other characters shine)
Eleven - doesn't have the screen presence for that kind of intensity, alas. He could pull off the speeches in his own style, but he's not hypnotic while doing them the same way Twelve is, and he definitely doesn't have the type of personality to pull off the wall. His best emotional episodes are smaller and closer to the heart, and Heaven Sent is anything but small.
Five - could not pull off the speeches or the wall or the puzzle. He's a sweetheart and a golden retriever but he's not nearly dramatic enough to carry a solo episode like that.
Two - same as Five, really
One - just... no. I can't pull out any reasons (it might just be that he's from an era of television that was so very different in how it constructed stories), but no
Fifteen - hasn't been around long enough for me to get a sense of his personality
Thirteen - never really had a consistent personality in the first place. or any good emotional episodes so I don't feel like I know her well enough to make a judgement call
Six - just straight-up haven't seen very much of his run so I couldn't say how he'd fit in Heaven Sent.
