Hau and Gladion are your rivals, and they are severely underwhelming for different reasons. Gladion is so angsty that even Hugh from Black 2/White 2 would be put to shame. He just showed up, got beaten, and left. He admittedly became much more interesting later on, but by that point he's no longer a rival. Hau on the other hand was constantly beaming with optimism, even in serious situations.