Well gray is more clever but not stronger unless he had a deeper magic supply.Anybody weaker than Lucy if one on one meaning it is Rouge or Sting vs someone not both. I would've said Lucy but Leo and Capricorn should be able to handle them if one on one. It would be 3 vs 1 battle. Maybe they could beat Juvia mid difficulty alone. Rouge and Sting alone don't seem mega impressive. A fully healthy Gray could take on both since Gray>=Base Natsu and yes he has feats to back it up.
His attacks are just as powerful as Base Natsu attacks. Ice impact and Ice hammer hold a lot of Force + Ice wall and Ice Knuckles pack a punch. Natsu Attacks are more destructive but hold just the same amount of impact. Also SO gave Gray a lot of magic supply. Gray has some pretty powerful attacks but recently he has just been depending Swords and Lancer. Go read/watch the Gulana island arc to see what I mean it was he had his best moments in that arc which is sad considering he is suppose to have grown stronger.Well gray is more clever but not stronger unless he had a deeper magic supply.