They would have to clearly be at a decent power level otherwise it would make no sense. Trunks as a Super Saiyan fighting Base Gohan shows that the Base Level does not have to be in the millions but pretty dang high compared to an average Saiyan.
Gohan(1 arm): 3,250,000
Super Saiyan Trunks: 2,700,000
Base Trunks: 54,000
@p123 Vegeta and Goku needed an extreme emotional trigger to Transform. Goku had to watch his best friend murdered in front of him while being helpless. Vegeta's was an all consuming passion to be stronger and when he felt helpless he transformed. Future Trunks being a hybrid probably had an easier time of it just like his present counterpart. He just was weaker than his present day timeline.
Also how can we just disregard part of the Manga just because we dont like it? Couldnt we just do that with anything shown then? I do though prefer the anime.