Everyone can be good, I imagine, if you level them enough and give them decent gear, but I'm mostly concerned about her children and whatnot. I haven't been using her, but I'm early enough and my team is powerful enough that I can plug her in. Seems like she can only marry the created avatar character and only support link with one other person I don't have yet. Seems super limited. I'm getting to the point where I need to figure out who my main character will marry and which children are the best or whatever.
Not super in to the actual character stories (I mean I am to a degree, but lack of Master Seals have prevented me from getting Lissa and Maribelle to the point where they can damage and heal, which makes support linking them with the avatar character tough since he rarely take damage), but mostly I've been pairing people with those who cover weaknesses or help add range to attacks. So Vaike I paired with Miriel, Virion with Sully, Chrom with Sumia, and currently Lon'qu with the dark mage lady. My guy is a mage (well Mastered Tactician, but I mostly use tomes), but the only female melee characters I have are Panne (who I've been pairing with Donnel, along with the dragon girl since she can attack from range) and Anna. I guess there's Olivia as well, but she seems easily breakable and not all that strong. I just got her. I'm at B with Lissa, the dragon girl, Maribelle, Panne, and a couple of dudes, but have been hesitant to pull the trigger.
It seems, since she can attack and heal, that Anna is incredibly versatile, but realistically so is my main character. So does Anna get "Donnel good" if I level her up enough/advance her and is her child fantastic, or does the lack of support with anyone else ruin her? I know there are already "who did you marry threads" so I won't bother asking that, but I guess I need to decide pretty soon.
Do Panne and the dragon girl top off as well? Like they can't be Master sealed, and if I Secondary Seal them it looks like they can't use the dragonstone or the beaststones, which are pretty strong. Not sure if I should stop taking them in to battle because I feel like those are pretty strong weapons, but if they won't get EXP after hitting 20 it seems like it doesn't matter.