I'm not sure where you got that from, since Misty/Brock were generally poor battlers in the original series, and outside of Brock having knowledge about Pokemon, he was barely, "competent." We got better battles out of Clemont and Kiawe in their sagas than Brock, and Cilan too. Likewise May gave us better battlers than all the girls besides Dawn, since Iris didn't battle much outside the don battle tournaments.In most cases where there was only a trio, his companions turned out to be much more competent!