That list seems so wrong.. Anyways, here is my list which seems more plausible
Xemnas- for obvious reasons, he is the leader, feared by all, can turn other members to DUSK and turn things into NOTHINGNESS!!
Saix- second in command, respected by most members, Xemnas right hand man and Berserk.
Xigbar- he was the previous 2nd in command among the elder members according to the novels, he seems ver cocky and confident, described as being very skillful in battle and has experience. Seems to do whatever he wants and takes no one seriously besides Xemnas
Marluxia/Axel- both seem ver powerful and seemed to be equal when they battled each other in Chain of memories.
Xaldin- very skillful in battle, seems to have high authority over other members and very no nonsense guy.
Lexeaus- he is very powerful physically but overall he doesnt seem the best. He is very slow in battle (as it was shown when he got outsmarted by Ansem-riku) and his speed gives him a huge disadvantage when fighting against other faster members who can teleport fast.
Larxene- among the fastest member, stronger than riku replica, seems overconfident
Demyx- has potential, but due to being a coward he does reach his full power, also a sloppy fighter and inexperience.
Vexen- has more defense than defense and is only good for research and experimental things. In the battlefield he is not as good as the other members and uses Defense strategies more than fighting.
Zexion and Luxord- they are both not fighters and use techniques,a nd tricks to do mmost of their battles so it is hard to place them on the list. Luxord SUCKS at manipulating time and relies too heavily on cambling and games of luck! Zexion is good with illusions, but when the enemy figures his tricks out, he becomes very helpless....