I managed to dig up some data about the Trainer's stats for Festival Plaza, Hall of Fame and the like.
They are in the following addresses in HxD
1D28: Starter Pokemon
Rowlet: 00
Litten: 01
Popplio: 02
1254: Trainer skin color (use the corresponding values for your player gender)
Male 1 (Pale): 00
Male 2 (Default): 08
Male 3 (Tan): 10
Male 4 (Dark): 18
Female 1 (Pale): 04
Female 2 (Default): 0C
Female 3 (Tan): 14
Female 4 (Dark): 1C
127A: Battle
I found the offset controlling shininess of non-legends, it's offset 0x4535.
0x00 for non-shiny, 0x01 for shiny. (Changing that made my shiny Barbaracle into standard Barbaracle)
This table will document the various values, as I move along.
edit: Consider setting these unset too: 0072, 4269, 4538
old words: