OK having thoughts of an 'Everyone has an Eevee' au
Ren gets an Eevee shortly after the Probation news broke as a "Therapy Pokemon". It becomes the most spoiled Eevee in the world. Its friendship is max but won't evolve because "But what if he gets hurt :("
Ryuji got the Eevee as a gift for making it to highschool. His mother bought a thunderstone for unrelated reasons but through a series of unfortunate events, the Eevee got a hold of it and is now a Jolteon :)
Ann got an Eevee when she was very young to have as a companion when her parents are away. Sometime in middle school, she had a very serious discussion about evolution and the Eevee evolved into Flareon
Yusuke didn't have an Eevee until becoming friends with the thieves. (Sort of like a 'Sorry for completely uprooting your life and making you come to the realization that your guardian is a piece of shit' present). It didn't take long until he spent an unreasonable amount of money on an Ice stone. Not for evolution purposes, but...
Makoto is in the same camp as Ann in that she got the Eevee very young. When her dad died and Sae started to focus more on work, they pretty much became inseparable, and in the same boat as Ren with not participating in battles. However, during the Kaneshiro fiasco, there became no choice and the Eevee evolved into Espeon immediately to protect Makoto
If Ren has "The Most Spoiled Eevee in the World" then Futaba has the Most Miserable. Not because she doesn't take care of it (Other than during when she had her palace, in which Sojiro was taking care of it more than she was. Futaba is trying to rectify that now) but because it evolved into a Vaporeon.
Haru got her Eevee around the time when her engagement started. She took care of it but never really attempted to get attached. Later, after her father died, she started taking the Eevee to the planters to have a companion. It wasn't long until she now had a Leafeon :)
Sumire has a Sylveon. It was originally Kasumi's, but after her death it became hers. During the events of the game, it could tell something was off, so it didn't like being around Sumire as much. This concerns Sumire who is like "Omg why does my Sylveon hate me :0" and she tries talking to Maruki/Ren about it. Later, after the brainwashing wears off, they make up
Akechi only gets one Post-canon due to thief insistence. And boy if you think RENS is spoiled well...this Eevee is living it's absolute best life. Unlike Ren's it does end up evolving due to one of Shido's croneys trying to ambush him. A chomp to the legs was enough to evolve it into Umbreon















