Kuro makes me think of the kind of guy who's intelligent, but also real smarmy and full of himself. Maybe someone who, under different circumstances, might've been Fern's buddy or lackey.
Lucia looks a lot like Victoria (so much so that at first I thought they were the same character... XD), so I thought they might be related. I think she someone who can sometimes be a little too serious, and is also going through some punk or defiant stage in her life ("I hate you, mom! I'm moving to Reborn, so NYEH!").
Ari seems independent and headstrong, the type of person who will not take your s*** and will keep on trucking, no matter the circumstances. Insults and obstacles mean nothing to xyr, xe'll just soft reset grind a couple levels higher each time until xe wins.
Decibel seems like xe would rather not be there at all, let alone get stuck with a whole bunch of "buddies" to "help" xyr along xyr journey. Get the badges, beat the bad guys (if xe really has to) and go home. The end.
Black-Haired Boy wants to be the very best, like no one ever waaas~ Like Lucia, he can be way too serious sometimes, but overall cares a lot about his Pokemon and the friends he's made on his journey.
Blondie is Annie from Gunnerkrigg Court.