Hi, so I saw the GitHub Respiratory & I'd say the 4 forks (Reborn AI, Gen 8, MKXP, & optimizing code) cover the majority of what one would want for Essentials v19.
I'd like to offer 4 more suggestions for Essentials:
1) (from Sun/Moon) When catching a Pokemon while your party is full, after the Pokedex updates, you can choose to swap out a Pokemon in your party to add the newly caught Pokemon. Like what this script does: (broken link removed)
2) Upon changing the terrain (Electric/Misty/Psychic/Grassy), the battle background changes to match the newly set terrain, & after the terrain ends, the battle background reverts to what it was at the start of battle. (New battle backgrounds for the 4 terrains can be made by copying some of the ripped HGSS/DPP backgrounds & shifting the hue/saturation)
3) setbattlerule("randomlead") an option to randomize the party order of an opposing trainer, instead of leading with the first defined Pokemon in trainers.txt every time.
4) (from HGSS & Gen 5) New optional field(s) in trainers.txt "ace= true, 'dialogue', 'music.ogg' " that when set to true, the opponent trainer won't send out the last defined Pokemon until all other Pokemon have been KO'ed. "dialogue" and "music.ogg" are optional parameters that allow for the opponent trainer to make a speech (Gen 4+) & a change in music upon sending out the ace (Gen 5)
- If both suggestions 3 & 4 are implemented & set to true, the ace will still go last