I'm using Fred and Libra in my current run. Fred is the support unit/husband to Sumia, to give her some much-needed strength and defense. Libra is in because I needed a healer after switching Lissa and Maribelle to the Peg Knight tree, but he's doing better in the role than they were.
Generally, no, because Pre-promotes are garbage once you get into the game and everyone's stats have caught-up to them, except that everyone else can still promote and gain 20 more levels, while they're stuck with what they got.
In this game, though, it's less of an issue. You can just Second Seal them around and their stats will grow just the same as anyone else's. So really it just comes down to which skills each character has access to with their classes.
"Not all who wander are lost." http://whitetigershiro.blogspot.com/
Just read other comments and noticed it included other FE games.
Then from all the games I played: FE6 - Nope, never iirc. (if you don't count Fa) FE7 - Even I never used Wallace - so nope. (if you don't count Athos) FE8 - My first Fire Emblem - I used practically all prepromotes, even post game they were pretty beast. Then I started realizing how stellar some units like Lute could've been if I used them/survived. So yes FE9 - Again, no.... (if you don't count Tibarn/Naesala/Nasir respectively) FE10 - practically everyone was promoted. But third tier promoted, I used Elincia. So yeah.
Now that I think about it I actually try my best NOT to use prepromotes. But considering the unlimited level ups this game has and the availability of Anna, yeah I ended up using her! Although I never touched Frederick or Say'ri.
Come to think of it, my first pt has always been a blessed prepromote tun Anyway:
FE1 - exception, Marth is a god. Does not stop me from turning Jeigan into a god who soloed a majority of final chapter FE3 - Arran, no. Sirius is pretty godly and he is the original oifaye so..... FE4 - I have bad luck with Quan, and Oifaye. My mvp ended up to be Finn and gen 2 gamebreaker in general such as Celice FE5 - choose to deploy Dagda for most of the game. Dagda ended the game with 15 speed, skill, and 20 str. Bryton and Finn(they are a Jeigan because I say so) are pretty hax, alhough only Finn remains a hax in my repeated pt FE6 - Marcus cap rammed speed and strength and has like 15 defense during endgame. Zealot is only a bit worse, having skill problem No, seriously FE7 - at level 15, Marcus has 22 Str, 18 spd, capped Skill, 17 res, and like 14 def. FE8 - Sethsolo FE11 - I am too busy to use Sheeda to give a damn