I have a merged +spd Fallen Mareeta with galeforce and I’ve been thinking if I should give her Lull Spd/Def. I know that her natural B skill Null Follow-up makes her really useful against some foes, but it has no effect on most of them and many of those that it does have effect usually have really high defense, making it hard for her to defeat them. What do you think?
NFU is a great skill for a unit you want to battle Armored Foes. While there are other uses, especially since IS likes to give the occasional Slower non-armored units Automatic Follow-up/Follow-up denial Prfs, Armor foes are going to give you the most mileage from it.
That said if you you have another role in mind for her than there are probably better B skills.
I’ve had the same problem with mine awhile back.Lull spd/def is a good option,special spiral for Aether spam is what I use.