i guess the re-gym linking partner isnt that need since re gym is already really easy to deal with, and it also got many bug possibilities like what above stated, so i might not suggest to improve to that part such as "beat NPC together", except the whole like 'purpose of playing this game', for ex. battle tower and doubles-link tournaments, or maybe even duo-Elite4 link battle (i think about the mechanics probably we will just put it to 2v2 battles with 3maximum pkmns each users like BF?).
to respond this suggestion above:
- Story; So, new players can link play with their link partner{friend/couple/stranger} (i know this one might be hard to implement)
instead of 'battling side-by-side' along the storyline, or even to answer 'the buggy whos the lead? thing'..., it might deal with several bugs and wouldve end in stuck for month-by-month. so i suggest the alternate. the battle Link system for regular NPC battles does share the exp that obtained from any each link member battles, like exp. share item doe, but its in link, any link member that defeat a trainer or wild pokemon, and get exp from them, the other link teammates also get amount of exp (only the lead pokemon) with the maximum of exp gain is halfed or 75% (depends on decision) of total regular exp gained. and also, this ONLY can be applied while the members of link is in nearby (mean if you are in route 1, your teammates is also shud be in route 1, other side, the link benefit wont apply).