I think this whole Kaguya vs Momoshiki debate can probably be settled in another separate thread tbh, because it's such a controversial topic it'll definitely clog this thread more than is necessary.
We don't really need it for establishing a scaling chain. Here's an example of what we can go with (for now):
Baryon Mode Naruto >= Isshiki > Partial Ōtsutsuki Jigen > Other Ōtsutsuki tier characters (SPSM Naruto and Rinnegan Sasuke [Adult and Teen], Kaguya, Momoshiki, Kinshiki, Madara, Hagoromo, Possibly Hamura, Delta, and Kashin koji) > BSM Naruto (The Last) >> TCM Toneri
The low 5-Bs:
- Baryon Mode Naruto: Fought Isshiki, and initially overpowered him, so he obviously scales.
- Isshiki Ōtsutsuki: Stomped Naruto and Sasuke, and is stronger than Jigen who did the same.
- Jigen: Stomped Naruto and Sasuke, though he had to use his full power to do so.
- SPSM Naruto (Teen and Adult): He scales by virtue of being far above his BSM state from the Last.
- Sasuke: Equal to Naruto as an adult, so he scales.
- Fused Momoshiki: Can keep up with Naruto and Sasuke simultaneously, though both were not at full power, and he was still overwhelmed when they went all out.
- Base Momoshiki: With Ninjutsu, he managed to knock out SPSM Naruto. Physically he should be comparable to or superior to Kinshiki.
- Kinshiki: He kept up with a casual/held back base Sasuke physically.
- Kaguya: Much stronger than Teen Naruto and Sasuke, and casually killed hundreds of Naruto's clones, tanked his TBBRS, broke Sasuke's Perfect Susano'o, etc..
- Hagoromo: Betsowed upon Naruto and Sasuke their Six Paths power, and fought Kaguya in the past. He also became the Jubi Jinchuuriki, and became even stronger.
- Hamura: Should be superior to Toneri, and fought Kaguya alongside his brother. Though he is probably weaker.
- Madara: Fought SPSM Naruto and Sasuke.
- Delta: Fought SPSM Naruto, though he was somewhat holding back.
The 5-C+ tiers:
- TCM Toneri and BSM Naruto for scaling to Toneri's feats. Naruto would potentially be "At least 5-C+" for scaling significantly above Toneri.
5-C (56.271525956 exatons to 71.062 exatons) tier:
Kashin Koji: scales to 10% Jigen in base, and roughly 10x that in SM.
Sorry if I missed anybody, but I think this should be the basic idea for the scaling chain.