They say that owls are symbols of wisdom and knowledge. Apparently Coo missed the memo on that because the only thing he cares about is showing off and picking up chicks. Coo's not the smartest one in Kirby's dream team, but when it comes to battle he's strong, fast, and always hits his target. Coo is full of bravado and thinks very highly of himself. His most prized possession are the feathers that make up his hair... and a leather jacket he bought in one of the earliest Kirby's Adventures stories. Believing he wrote the book on "game", he also esteems himself as God's gift to women. Of course, he is always rejected. He remains steadfast and perhaps a little hardheaded, never blaming himself for the reason why women don't like him, but the women themselves (it doesn't help that he's typically way younger than the girls he hits on). He has a short attention span and being more hands on, doesn't grasp abstract concepts very well, so he doesn't do too hot academically. This causes him to stop trying, leading to more underwhelming grades, and thus creating a negative feedback loop. He does seem to do a lot better in classes where there's more hands on participation.
In Kirby's Adventures, Coo has always had a personality of a wannabe gangster, like something out of Goodfellas, though he probably comes off more like something out of Jersey Shore. This is more the fact that he just wants to get respect, so he plays the tough guy, and will beat others up with little provocation if he gets annoyed enough. That said, keep in mind that Coo is still rather young, and when the facade drops, he acts like you'd expect a thirteen year old boy to. Later on in the series, it's shown that there is indeed a mafia-like outfit run by similar owls of Coo's species. This personality of course has carried over, much like everything else, into Alternate Universe, and the Owl Mafia has made it into the series, too.
Coo's relationship to Kirby is a respectful and friendly one. Being something of a fan of Kirby's he's always excited to go on adventures with him in hopes of becoming stronger and well known just like Kirby. He also just likes hanging out with the guy. Coo also has respect for Kine, seeing as he understands just how valuable it is to have someone as smart as him around. Plus, Kine helps Coo out academically, and since Coo is always trying to do his best in his parents eyes, is appreciative of the time Kine spends with him. He's also sort of afraid of him, as he doesn't quite grasp Kine's sarcasm sometimes, and feels like Kine can be even meaner than he is. Rick, on the other hand, is where we have a problem. Coo and Rick are usually at each other's throat for no valid reason at all. In fact, Coo's reasons for animosity towards Rick are merely "just because", "I don't like his face", "he ruffles my feathers" or "because he's stupid". Coo usually doesn't refer to Rick by name and just refers to him as "the hamster". It's possible that they only fight with each other relentlessly because they both have larger-than-life, attention seeking personalities, and it's possible that they could be projecting something they don't like about themselves onto the other. When the dust settles and they get the fight out of them, though, Coo and Rick seem to share a camaraderie, as they tend to finish each others thoughts, jokes, and sick burns. They get along well when someone else is their target and not each other, and they tend to get excited for each other, rather than envious, when something good happens to the other. A very complicated relationship indeed...