Strong Pokemon... Weak Pokemon...
That is only the selfish perception of people...
Personally, as a traditional martial artist who has branched off, I enjoy MMA, but tend to not be eligible to partake in it, even if I wanted to. After years of working with traditional martial arts, my natural reflexes would cause me penalties and faults all over the place if I tried doing MMA. Though I am interested in the style, and I have looked at it a bit before, it's not a thing that works out for me.
Truly skilled Trainers should try to win...
With the Pokemon they love best.