What do I do with all of these random friend invitations!?
Start adding. I was hesitant at first, but then I quickly realized that this is a vital part of the game.
For now, after you've added everyone on here that you want, pick people with mons that might work with your team. You might have noticed that before you enter a dungeon, you can pick from a bunch of randoms, and some of them will give you 5 points. You can pick them, but their leader skills won't activate(Though it'll give you a prompt to friend them after). Only people you've friended will have their leader skills work, and they can stack with your own leader's skill! (Boosts are multiplicative, so that's 9x ATK if you somehow friend another Sun Quan, which means a lot of pain for the enemy.)
Though, you should just friend as many people as you can, and maybe leave 1-3 slots open incase you see a random with a good lead you want to try grabbing. I did this and grabbed some other Suzakus since that fest was still going on. This'll help you get a lot of Pal Points, and with the Pal Machine event going on right now, this could save you a LOT of headache later if you get lucky.
Also, don't be shy about deleting randoms who have leads that don't benefit you as much anymore in favor of better ones - You'll want to progress through the game with a better friendlist, because their dudes end up being just as important as your own, especially in the later stages.