Anyone who runs away after X turns or has to be recruited among a crowd of enemies. Looking at you, Amelia, Rennac, and Marisa.
My opinion hasn't changed, but I'd like to add the fight with Aversa to that list. IIRC she starts as a green unit and thinks that she can actually fight your team. Of course, she can't at all. This was a real problem for me on my first run, as I had over-grinded a select few of my units by the time her DLC came out. I ended up needing to field a bunch of crappy Bonus Box units so my MVPs could easily take down most of the opposition.