User blog comment:Imperial Wyrm/King Kai's full power/@comment-15906818-20160608183356

Despite his position, he is not as strong as Pikkon or Goku, due to having neglected his training. This is why he uses the full breadth of the rules to keep from having to teach either of them immediately at the conclusion of the Other World Tournament.

That is from Grand Kai's page.. It's possible that King Kai may have been stronger than GK at that point.