Elio has a naturally charismatic air about him that easily pairs well with his generally friendly, generous, optimistic, and brotherly nature - so he makes friends very easily, and at times - quickly. He's someone you can depend on in most situations, even at times when it's out of his depth; in which case, he's there for moral support.

While not exactly chatty, due to his affluent background - coming from one of the most powerful families in all of Unova, his upbringing was slightly strict in some aspects, and as I explained in another ask, due to his family being self-imposed perfectionists, he's mastered a variety of skills which that fall into a multitude of areas. So being an expert conversationalist is something to be expected of him. In short, he can definitely hold a conversation and show a keen sense of interest in respect to the other party.