As a person who enjoys playing monotypes, I definitely don't mind type overlap. However, regarding my main playthrough teams, I tend to use my favorites. As a result, sometimes, my team would have some Pokémon that shared a type. For instance, in many games, because Starmie is my all-time favorite Pokémon and Gardevoir is one of my favorites, I tend to have them on the same team, and they're both Psychic types. Also, I sometimes have Lucario and Magnezone on the same team, which are both part Steel-types. However, if it's just an in-game playthrough, I don't worry too much about it because the NCPs never give me much of a challenge anyways. Yet, if types overlap, I try to have more than two of the same type on a team. Nonetheless, I did build a Gym Leader Water-type team, which I actually did use in Pokémon Sword, and it is really good. Of course, every Pokémon shares the Water-type and I really love to that team.