I recently got into the FE franchise. Thanks to Dolphin, I am now able to play FE9, which I never got around to when I still had a GameCube (and a TV). My first playthrough was a female-only "challenge", which turned out to not be much of a challenge. The female cast has quite a number of broken units, including Marcia, Jill, Astrid, Titania, etc. For my second playthrough, I decided to stick to a single character, and after much deliberation settled on... Mist.
In this playthrough, I will only use Mist once she becomes available in ch9. From ch10 onwards, I will only deploy (unarmed) Ike and Mist. This will all happen on Hard mode with fixed growths. The obvious challenge is that Mist's strength cap is a meager 20 (16 natural). She is also sadly unable to heal herself.
Promoting Mist was more challenging than I expected, as the pirate with the Hand Axe kept killing her. I won't be winning efficiency awards any time soon.