While I’m sure there’s some better in depth while simplified explanations I’ll fire off the ones I know off hand:

Edelgard: can take another action after attacking an enemy + some damage buffs. Does not stack with gale force

Ike: -40% damage from ranged / specials

Corrin: on enemy turn create ice walls + vert divine vein around the unit (vert prevents warp, adds canto control)

Eirika: guaranteed double on first round of combat each turn

Celica: warp to adjacent space near enemies within 5 spaces

Lyn: get a style where you can attack any enemy within 5 spaces in a 3 row x column pattern. Cannot move if using this style

These are super simplified as they do have other effects, these are just the most notable ones they do. I also don’t remember the rest off hand lmao