I'll try to give you an impartial judgement of the characters. So, let's see...
Dawn - She was undoubtedly one of the most developed girls, if not the most developed. She got plenty of episodes for herself, where we saw her progressing and learning from her mistakes. Another important part of her is her losing streak, in which she ended up going through a depression arc. Her team was also relatively well developed and overall they all were good both at battling and at performing.
Serena - She has a very slow start, but after that her development starts kicking in and fleshing her out more as a character. She rarely battles, but her personality and vibrant team make up for this particular "flaw".
DP Team Rocket - They are essentially a comedic trio, which pulls all kinds of mechas to try to get Pikachu or the Pokemon of the day. They showed a lot of emotions back then, which sadly ended up lost during BW. Also, Jessie was a good Coordinator, and managed to reach the Grand Festival. They weren't bad, but could considered by some very repetitive.
XY Team Rocket - Take the lack of emotions from BW Team Rocket and the repetitiveness of DP Team Rocket and you get XY Team Rocket. They have very few moments focused on them, but luckily those moments are quite important. They also come out with more clever plans, from what I have seen.