This is a hard question because there's so many scenes that I enjoy from the Dead Moon arc and it's unquestionably the best written and tightest arc of the manga, hands down.
However, one thing I have noticed is that the second half of Dead Moon feels a bit rushed and sloppy. There are quite a few scenes that's just Uranus and Venus screaming"PRINCE!" and "PRINCESS!" which definitely needs to be altered because on screen it's going to feel tedious.
I don't have the book in front of me, but all of the fake-out kills were also a bit shoddily done for the sake of creating a dramatic cliffhanger... I feel a lot of the back-half could be simplified and feel a little less chaotic. Thankfully, we have a new writer, so I have faith.
Other scenes I have no issue with being removed:
- Artemis CREEPING on Minako in the shower. NOPE!
- The scene with Mamoru and Chibi!Usagi where they try to get in the mood (?!). Another NOPE. I could also do without Chibi!Usagi kissing Mamoru.
- The Inners going to one of the Dead Moon shows again. Pretty pointless, although I like them taking initiative and the Quartet spying on them.
- The sleepover scene with Usagi, Chibiusa and Mamoru can be simplified a bitsy... It felt a bit long in the manga, and with this being a movie, I'm fine with being trimmed down a bit.
- Chibiusa hypnotizing Ikuko-mama - only out of respect for Ikuko-mama's old VA and this is not quite an important scene.
- Honestly, they could remove all Shitennou scenes and I wouldn't really care! Sorry not sorry. (They'll most likely keep it though.)