Why did Paul release his Pokemon without second thoughts?
Paul usually saw them as not very strong. He was catching Starly just to find one that knew Aerial Ace but he wasnt a fan of its battling skill so he released it as well. He had caught an Azumarill at some point since he likely knew Roark, the Oreburgh City Gym Leader was a Rock-type specialist and its known that Water-types are strong against Rock-types but because it likely was recently caught and didnt have much training in it got defeated pretty quickly so he gave it to another Trainer. Now in the case of Chimchar he kept on trying to get it to activate Blaze since thats what he saw in terms of the power that he wanted on his team but it was never able to since abilities dont always activate on their Pokemon in fact some abilities activate either randomly or only under certain circumstances anyway Paul felt it wasnt living up to its potential so he just gave up with it and released it.