It's a work in progress, but 2K's "Dynamic Duo" system in MyTEAM is one element you'll probably be seeing in future editions of the game.
MyTEAM's new, friendship-rewarding mechanic is pretty straightforward: if you play these two player cards at the same time, on the same team, they will receive boosts to certain attributes that take them to the next level.
The duos are a fun way of highlighting real-life player friendships and changing in-game strategies, and some make more sense than others (see: Nikola Jokic and Fat Lever).
In any case, I've gone ahead and ranked the top 20 Dynamic Duo pairings currently in NBA 2K17—a process that involving weighing the total attributes boosted against the quality of the duo and the likelihood of you ever actually using them.