I am an old school player and never got past Gen II but man did I play the heck out of those games. Anyways the whole evolving based on friendship or the skill “Return” how do I tell how much a Pokemon likes me? Also is teaching “Return” to my starter Eevee a good idea?
You can turn and talk to your Pokemon and it will say that it likes to be with you or still undecided for traveling with you and if it said that it likes nothing more than being with you it means it likes you a lot and you can teach it return
In recent pokemon games, including Insurgence, TMs do not disappear when you teach them to a pokemon; you can reuse them indefinitely. So yeah, feel free to teach Eevee Return, and if you feel later on that you don’t need it, you can forget it. No loss.
In the course of normal play, friendship will naturally rise. Giving the pokemon a Soothe Bell to hold makes this go faster. Return becomes a 102 base power move at max friendship.