Yamcha wins easily, since Roshi thought that King Chappa was going to be a great challenge for a Goku who trained for 3 years. While Roshi didn't have high expectations in Goku's training, it's still an indicator that Roshi expected Goku to progress a certain amount. Therefore King Chappa is >> Son Gohan. Krillin hoped to at least rival and have a chance against a Goku capable of easily killing King Chappa. Considering that Goku after easily defeating King Chappa, told Krillin that if he had fought seriously, he would have easily killed King Chappa. Yamcha is on the same level as Krillin in TB22 and also has better techniques.
Goku SSJB Kaioken x30 (Top ToP) vs Kefla SSJ?
Both are from the Anime and neither has tension, nor time limit.