>>41198517But would he have become Gym leader if he wasn't also a Mafia boss or was he a Gym leader because he was a Mafia boss?
The Gym leader job may have simply been a cover for himself, a false job to cover up his real job as a master criminal, though if the Gen V pokemon world tournament says anything, sometime after G\S\C\HG\SS he decided to make his fake job his real job and went straight.
That arguably makes him higher than a shit tier because a shit tier villain never changes.
When Giovanni was finally removed of the responsiblity of being Team Rocket's leader then and only then he reformed.
But as long as he had to be Giovanni the leader of Team Rocket, that's all he ever knew.
And arguably considering how he loses to children every time, it was likely that he realized that he sucked at being a Mafia boss and had more fulfillment as a Gym Leader.