Who are the "difficult" characters?

I know that everybody can be played in rather simple ways, but some characters are absolutely more difficult than others when trying to master/optimize them. In that regard, I think that Base Vegeta, Blue Goku and Trunks are hard to play for sure. Who else would make that list? Why would they make that list?

Trunks downplay will be ignored, btw.

A very important clarification I want to make is that difficult characters ought to be separate from the bad and "weird" ones. I find that a lot of people say Bardock, Yamcha, Piccolo and Base Goku are terrible, but that's definitely a different thing from much better characters who require strict timing for a lot of their best combos. As for the weird characters, I could see the case being made for Frieza, Hit or Nappa. They just have some tools that are strange in comparison to a large portion of the cast. I don't know if they should be on the "difficult" list, though.

The only person I know of with a good video about this is LotusAsakura.
Lotus getting started:
https://youtu.be/8LhEAXwa38E?t=117
Lotus finishing up:
https://youtu.be/8LhEAXwa38E?t=1331