IV Question

What? Elaborate please.

There really isn't anything TO do about IVs except for getting another unit with different IVs.

Let's say we have a Marth. If you check his stats when he's level 1, or level 40, then you'll be able to see what his IVs are. For the sake of the example, we'll say Marth A has a boon of speed and a bane of attack. And, again, for the sake of the example, you don't want to build a Marth that has a bane in attack, so you, later on, pull another Marth, Marth B, and has a boon in speed and a bane in HP, and think that these are better IVs for him, you can choose to build Marth B instead of Marth A, and even (if you want to) merge them together.

IVs are, basically, stats that can differ depending on the IV set. Not every Marth will have the same exact stats because of the possibility of having different IVs (unless you manage to pull Marth's with the exact same IVs).

The only units that don't have different IVs are Grand-Hero Battle units and Tempest Trial units. You may also get units from story mode (Fjorm) but that's pretty rare.

Hope this helped.

You mean how to check IVs generally or how to decide builds based on a particular IV?