I think we have a solid conclusion with open ends for a later CRT regarding the likes of Ceadeus, Dah'ren, etc.
High 6-C --> Kushala + Nergigante, Ruiner Nergigante, Teostra, Lunastra, Velkhana, Espinas, Savage Deviljho, Rajang, Blackveil Vaal Hazak, Furious Rajang, Bazelgeuse, Seething Bazelgeuse, Deviljho
* (Can fight on equal terms with Kushala Daora)
High 6-C --> Vaal Hazak, Chameleos
* (Comparable to Kushala Daora)
At least High 8-C, possibly High 6-C --> Gold Rathian, Silver Rathalos, Abyssal Lagiacrus, Lucent Nargacuga, Molten Tigrex
* (Comparable to Gold Rathian and Silver Rathalos, who were theorized to be nesting in Nergigante territory)
High 6-C --> Amatsu, Akantor, Ukanlos, Crimson Glow Valstrax, Ahtal-Ka, Nakarkos, Yama Tsukami
* (Has higher hunting rewards than Kushala Daora, so should be at least comparable to it)
Low 6-B --> Gogmazios
* (Should scale to Shah Dalamadur)
Deviants might scale to Hellblade's calc, but since not all deviants are encountered in the same Low/High/G Rank, and they have widely varying HRP rewards, it's iffy.
Other variation species should scale to their base form unless we get evidence to the contrary
On the others, I have no clue.
All "Comparable" ratings here are based on the HRP metric.
