UTIMATE tips! making friends in Yo-Kai Watch

Just be my friend already!
Yo-Kai Watch recently released in the west earlier this month. I've been having a blast with it, but I've also been having some difficulties as well. So far I haven't been able to find any good guides to help walk me through some of the game's more confusing aspects, such as befriending Yo-Kai.
It seems to be largely luck-based, as Yo-Kai will randomly come up to the player after a battle and ask to be friends. This can be a bit frustrating, especially when a side quest requires a specific Yo-Kai or when you come across that one Yo-Kai that you just have to have in your party. I found myself battling about 50 or so Noways before one of them finally decided to join me, which is when I decided there must be an easier way.
Thankfully, there are a few methods which can be used to increase your chances of making friends in Yo-Kai Watch.

The main thing you'll want to do when trying to befriend a certain Yo-Kai is figure out which type of food is its favorite. This can be a bit difficult, as there's no way to know for sure without throwing a bunch of different things at it and seeing which one it likes best. Plus, there are a ton of food types to choose from (rice balls, bread, candy, milk, burgers, ramen, vegetables, meat, and more). Some of them are easy to guess: for example, Mochismo, the Yo-Kai based on mochi, likes rice balls; and Chummer, the shark Yo-Kai who can be seen eating grass, likes vegetables. For everyone else, it might be simpler to just look up a guide rather than waste a bunch of food trying to figure out what they like the most. The best guide I've come across can be found here.
When using food during battle, press the Y button to use the food on an enemy rather than a member of your party. The food will usually be eaten by the center enemy in battle, so if you're looking to befriend a different one, either defeat the middle Yo-Kai first and then use a food item, or place a pin on the enemy you want to focus on. Strangely enough, it can sometimes end up that a Yo-Kai other than the one you threw food at will ask to be friends after the battle, which can be annoying, but it happens.
Another good tip for making friends is to try and find a Yo-Kai with the Popularity skill. This skill makes foes more likely to become friendly after battle, so it's always a good idea to have someone with this skill on your team while hunting for new pals. Yo-Kai with the Popularity skill include Cupistol, Casanuva, Shmoopie, and Pinkipoo. But make sure you don't have Casanono or Pookivil on your team, because their Unpopularity skill might scare potential friends away.
Cupistol and Shmoopie can be found relatively early on, so they will probably be the best bet for players just starting out. Cupistol is a rank D Yo-Kai who can be found in the Downtown area around Graduate Street to the north. Look around the trees there for a rank D to appear on your watch. Cupistol will also sometimes appear along with Happierre, a rank C Yo-Kai who can be found in the trees in that same area. Make sure to bring lots of bread when trying to befriend Cupistol.

Shmoopie is a rank C Yo-Kai who can be found in the grassy patches of Mount Wildwood. I believe this one always appears alone, so no need to worry about accidentally befriending someone else. Shmoopie likes hamburgers, so stock up on those before hunting for him.
The other two, Casanuva and Pinkipoo, can only be found later in the game. Casanuva can be evolved from a Cupistol if fused with the Love Buster item. Likewise, Pinkipoo can be evolved from Shmoopie when combined with the Love Scepter. They can also be found in the wild. Casanuva likes to hang out in Nocturne Hospital, sometimes alone and often as a counterpart with Betterfly or Compunzer. Pinkipoo can be found in the final area of the game, which is maybe a bit spoilery so I won't get into it here, but you'll know it when you see it. Both Casanuva and Pinkipoo enjoy the same food as their unevolved forms (bread and hamburgers, respectively).
The final tip is a bit more unreliable, but if you get lucky it can really help. Occasionally during battle, a floating wisp will appear which can be hit with a pin for various rewards. Sometimes, a bunch of hearts will pop out of the wisp, which means foes will be much more likely to become friendly after the battle. It's not something you can count on, but if you ever see a wisp during a fight with a Yo-Kai that you really want, be sure to hit it with a pin just in case!
Of course, even after doing all of this, there's still a chance that the Yo-Kai will not want to be your friend, which can be frustrating. But these tips should increase your chances significantly. I found that after obtaining a Casanuva, I was spending way less time grinding for friends, so apparently the Popularity skill works well, especially when combined with food. Just keep at it and eventually you'll have all the friends you could want!