I always liked the two characters as your friends in the game. I personally looked at them more as your casual pokemon researching friend, rather than your rival. With May and Brenden as the two characters that you meet multiple times in the game as your friend who occasionally battles you, they always talk about how they are helping out their father researching pokemon and filling up the pokedex, and they always made it pretty apparent that that was their main focus. That's why I don't really mind that they are the least intimidating and competitive rivals throughout the entirety of the franchise, their characters never seemed to be that obsessed with being the best trainers in the game, they just sort of are drifting across the region in hopes to see all of the regions pokemon for the purpose of continuing their fathers research.
It's also, in my opinion, refreshing that there are characters within the franchise who presents themselves as your friends rather than some jerk who says mean things and then tries desperately to beat you at all costs, Brendan and May feel like nice friendly kids, and I actually really like that.
Wally always felt more like the true rival in the game, since every time you meet him he explains that he wishes to overcome his illness and weakness by proving he's the best, specifically by defeating you, which sadly the poor sick boy never does.
I also always liked the fact that May and Brendan always seemed to have a slight attraction to your character, just giving even a slight hint of romance between the characters in the game, even if only implied, makes the characters appear more human and interesting as well as it brings your character to life. The fact that an NPC would suggest attraction to your character makes your character have appeal and charm which makes your character appear more lifelike and full of charisma, rather than how most of the characters were presented in the previous games, where no such appeal was ever really expanded on before May and Brendan.
