Hau was a good character if you looked closely, a decent rival with decent AI but a very good character...later on like around the Aether infiltration because he gets serious about saving Lillie. He was a little annoying sometimes but not as bad as the Kalos group.
The Kalos group had a great thing going, they were friends who let you into the group and let you have a nickname (I think I made them call me something like Lady Serena cause I'm mean like that) They were, in a way, travelling alongside you. Then it kind of stopped, they were still your friends but they just kind of randomly appeared and vanished. I barely remember what Trevor and Tierno said back then, Shauna's a little more memorable because of the palace, the random out of nowhere "makeup" scene during the final Team Flare confrontation, and the fact that she won't leave my lawn. The opposite rival is kind of interesting but I barely remember their story. I know Trevor lives alone with his sister in Lumiose but nothing came of that either. Shauna's the only one with a sidequest that was just with her. What they should've done was give each one a segment where they travel with you and you learn about them. You learn what Shauna wants to do with herself, why Tierno wants to be a dancer, why Trevor is so invested in the pokedex, and what drives the opposite rival.