Nuren

Known issue that we call "evotree". Basically, PKHeX doesn't account for changes in evolution methods between games. This will be fixed eventually, just not soon. You can read here if you want to know how big the problem is and what all has to be accounted for to fix it properly: https://github.com/kwsch/PKHeX/pull/3359#issuecomment-1003808371

This is a known issue that affects Pokemon that have moved through Bank and then HOME. The Pokémon are typically missing an HT language and have a link trade memory of being met "somewhere".

It isn't both options in BDSP; there is a specific list of Pokemon that require 255 friendship (they say "Ssshhhnnn..."), and everything else requires the 30 levels gained. Some examples: My met level 80 Arceus from SP does not get the ribbon even with 255 friendship and at level 100. My met level 70 Articuno from SP doesn't get the ribbon with 255 friendship, but does get it after it is at level 100. My met level 70 Regigigas from SP doesn't get the ribbon at level 100, but does get it after it gains 255 friendship.

Tree Pokemon IVs are generated with csprng as far as we know, not the same as Overworld8.

Should be fixed in development build / next stable release; thanks for the report!

There is no species-specific height/weight calculation for SWSH. Height and weight do not necessarily need to be correlated either; any height and weight combination for a given species can be generated by some specific case of the RNG. There are tall/thin Lopunny, tall/fat Lopunny, short/thin Lopunny, and short/fat Lopunny. Height and weight are triangularly distributed, which means middle values are more common than extremely small or large values. PKHeX only enforces height and weight for a few SWSH cases like overworld encounters (fishing, grass, overworld legends) and HOME events that are forced to have 0 height and weight. You can pretty much put any values for most encounters otherwise. PoGO encounters do have some correlation between height and weight that is not well described and not at all enforced. (Light mons tend to be short mons and heavy mons tend to be tall mons.)

After the next stable release (or if you use the current development build), all Colosseum Ho-Oh will correctly no longer appear with the fateful encounter flag.

Order matters. The game first assigns default moves and adding egg moves at the end pushes the early ones off.

Is it known that you cannot capture it with Curse from non-Crystal distro event raids? The only den I have verified can come with Curse is the rare purple ROM den. (Also this page still says it)

Can you clarify what this means? It is possible to catch a G-Max Copperajah out of the rom den with Curse as an egg move, and it should also be possible to transfer it onto G-Max Copperajah via the Nursery.