Shinji is a great foil to Satoshi, as has been pointed out in the anime multiple times. Same goals, different methods.
However, Shinji is not evil. He might be cruel, but he isn't doing it for abusive reasons. The only difference between him and that Sandslash trainer in the early episodes was that that unofficial gym leader was shown to love his Pokemon, whereis Shinji doesn't.
Does that mean his method, for Chimchar, wasn't cruel, or bad, or immoral? No. But I also think it was very out of character for Shinji, and in that case, he was just used as a plot device so Chimchar would get to Satoshi's team.