>>44823264raihan isn't canon because he's from swooshit.
>>44823161claire, giovanni, & blue are particularly strong. claire is just barely weaker than Lance, the strongest champion currently still reigning over their region. blue is pretty obvious, he was a previous champion and the main rival to one of the main protagonists, red. giovanni is remarkably strong thanks to his many displays.
other noteworthy mentions include juan, mentor of champion wallace, and volkner, confirmed to soon challenge the elite four.
drayden is presumably only slightly weaker than champion Iris due to comparative reasons, and since marlon is above him marlon gets special recognition.
wulfric is the strongest in kalos, but has nothing to back such a claim. thus, wulfric is weak until proven strong, especially since he has admitted that his gym challenge is easy to most.
