Back then, when Paul captured Chimchar, it was because of the terrifying Fierce Fire he saw Chimchar unleash. Under that Fierce Fire, Chimchar could exhibit power far beyond its own level.
At that time, Chimchar was still at the Ordinary Level, facing a group of Zangoose, and in the blink of an eye, it defeated them all!
And those Zangoose were at the Advanced Level, all above the Advanced Level.
This made Paul see Chimchar's potential abilities and decide to capture it to dig out its power.
But now, several months have passed, and not only has Chimchar's power not been uncovered, its level has been progressing very slowly.
So far, no matter how much Chimchar has been pushed to the brink, it has never been able to unleash that Super Blaze, and its progress in level has been far below that of other Pokémon he holds.
In this situation, Paul feels that having Chimchar is no longer meaningful to him.
Although he scolded Chimchar as useless during matches, that statement was actually more about himself—unable to draw out a Pokémon's power, he's just as useless.
With such progress, wanting to battle in the Pioneer Area and defeat Brandon seems like a distant goal.
He can't waste time on a Chimchar from which he can't extract power. He needs to look for other Pokémon with great talent, so he chooses to release Chimchar here.
He won't do something like leaving Chimchar with his brother, as that's meaningless and just delays both parties. Releasing Chimchar now is better for everyone.
"I've made it very clear, I don't need you, and you don't need me. I'm not the person who can trigger that power within you. It's just that simple, go your own way." Paul said, turning away, ready to leave without looking back.
"Stop!" A loud voice called out from behind Paul, making him turn his head to see Ash's angry face, with Pikachu next to him, looking furious though not appearing threatening.
Seeing Ash, Paul seemed somewhat intrigued. He turned, hands in his pockets, and said with a bit of interest and questioning, "Are you the Superstar from Kanto? I know you, in just half a year since your debut, you defeated a candidate for Elite, and recently you almost tied with Lorelei, the Elite."
"But your battle style is just like that, relying entirely on passion. If your Pokémon weren't strong enough, you wouldn't have beaten that Elite candidate."
Ash: ...
Do I even know you? Even though we've seen each other a few times, we haven't exchanged a word, have we? What's with this superior tone of evaluation? Anyone who doesn't know might think you're a Champion!
"What my fighting style is like is my business, I don't need you to teach me. We're all peers, and you have no right to instruct me. If you want to guide me, beat me first... More importantly, I want to talk about what you did to Chimchar!!"
Ash retorted to Paul with dissatisfaction, then turned the question back on him.
Regarding battle styles, everyone has different opinions; this naturally is shown in battles. But Paul's behavior completely defies logic.
"What did I do to Chimchar? I simply deemed it unsuitable and released him, that's all. Releasing Pokémon isn't uncommon, as long as it's done without silent abandonment and both sides' unsuitabilities are clarified, per league regulations, it's allowed." Paul explained coldly.
Abandonment of Pokémon has strict regulations from the league, but release, if reasoned and explained to the Pokémon without further complications, is considered a peaceful parting.
The league does not penalize this since you can't force a Pokémon and trainer to remain together if they aren't suited; it might cause bigger issues otherwise.
People like Damian are the real problem; he didn't clarify anything to Charmander and tried to abandon it secretly. When sneaky abandonment failed, he left Charmander behind with lies.
If not for Ash, Charmander would have died that night.
Such people would definitely face league sanctions, but not Paul. He clearly stated his unsuitability with Chimchar and explained it to him.
Even if reported to the league, Paul is in the right here; his reason may be inhumane, but it's not against regulations to penalize him.
"Putting aside your reasoning for releasing Chimchar, aren't the injuries on Chimchar from battles for you? Why haven't you taken him to a free Pokémon Center?"
Paul: ...
Paul glanced at the battered Chimchar, a strange emotion flickered in his eyes, but his cold demeanor covered it up again: "Unnecessary, these wounds are nothing to this guy. He'll recover soon, going to the Pokémon Center is just a waste of time."
"So what you're saying is... Chimchar has always been in this condition under your care, right?!" Ash clenched his fists, suppressing the fury brewing inside, speaking with controlled anger toward Paul.