Basically anything that would help make the single player campaign easier while also maximizing points earned, would be useful for a trainer.
Things such as:
Crowd Meters always a 5 stars (for max points)
Timer doesn't countdown for timed challenges (for max points)
Goal satisfaction timer always at maximum (for max points)
Edit XP (as mentioned above, its the music note icon in the character creation screen) and Style Points (sunglasses icon in the character creation screen, don't remember what they're called off the top of my head in-game) for faster unlocks
This official support page:
Link may assist in providing further context to the above for point scoring and where to explore possibilities for the trainer.
[Edited by gameztester, 11/14/2020 7:11:11 PM]