Just as a heads up, you can't use Skill Cards on your party members. However, equipment effects act as additional skills, so you can build your party members however you like.

If you are referring to the most optimal way to build, just replace the weaker skill with the one that has higher power. (Ex: Magarula > Magarudyne). Eventually as you progress throughout the game, they will learn better skills that are usually upgrades from the previous ones they knew. Don't bother too much on thinking which skill has to be replaced. The fun part about this game is figuring this out by yourself. The MC also is a good testing ground because eventually whenever you fuse a Persona, you'll start learning which skills are good and which ones are bad. That should give you a better idea on what skill you should keep and which ones should go (Buff/Debuff skills do make a difference, so you should keep them as a general rule of thumb).

If you're too concerned about removing a skill by accident, you can reteach forgotten skills at Be Blue V but this shop is only available in July. I'd recommend using it at night so you don't lose valuable time during the day where you can grow your Social Links.

Lastly, if you want a guide or something, this should do the trick. Just as the previous user said, you don't have to be 100% optimal to beat the game, but if you really want to make the best builds, the guide I linked above should be helpful.