Elio tolerates a lot of things AT BEST. Though he will bluntly voice his opinions.

If he does get angry, it's usually "righteous anger", and even then he would be methodically spiteful about it while making sure he doesn't go overboard.

However... If you're a Pokemon Hunter/Poacher, consider your life forfeit. Literally. At that point, he doesn't think of you as "human". It's free real estate. On-site every👏🏾single👏🏾 time👏🏾. And this mentality is backed by the fact that Pokemon Hunters/Poachers are responsible for some of the worst tragedies ever to rock his family, city, and Unova as a whole. He would NEVER forgive any of them responsible for multiple attempts at attempted kidnapping, terrorist plots, destruction of property costing millions of Pokèdollars in repair, smuggling dangerous foreign elements that can potentially cause breakdown in relations with other regions should they be discovered in Unova, and most importantly - being responsible for the death of his parents and maternal grandmother, which left his grandfather and older siblings in utter grief. He knows simply arresting them won't do any good since they have their connections and quite readily will get off scott-free.