I disagree about Citron. The only time he showed that he was an above average battler was during the Miare City Gym battle, and even then it seemed to me that he was only shown in that light to make the Gym match more intense. The writers weren't consistent enough with Citron's strength as a trainer after that point, so I don't think he was meant to be one of the strongest companions.
It says something when we were more liable to see Bunnelby get his ass brutally kicked by TEAM ROCKET than Pancham or Noibat even suffer a hit.
Then again, who suffers the Worf Effect more often than Ash's Pikachu?