How to IV/EV train your Yo-kai

1. Abuse the Yokai Cam feature to obtain a large amount of Holy Exp Orbs and Crank-a-Kai Coins. For reference, it takes 55 Holy Orbs to raise a level 1 S rank Yokai to level 99. You also may want the attitude altering books if you plan to change your Yokai's attitude right away.

2. Once you have the desired number of coins/orbs and the right books, save right in front of the Crank-a-Kai.

3. Now, begin using your coins. Use three at a time. I tend to keep going for the same color coin until an exclusive Yokai shows up.

4. Every time the Crank-a-Kai vanishes, save your file, and return to the home menu. Then, advance the day by one on your 3DS system clock. When you return to the game, a red oni will scold you for tampering with it, but there are no drawbacks aside from having to listen to him talk. The Crank-a-Kai will return if you did it correctly, allowing you to use it more than once a day.

5. Once an exclusive Yokai finally shows up, take note of how many coins you used. You can only use the Crank-a-Kai three times per go. So, assuming an exclusive Yokai showed up on the second coin you used, you would use one coin, and then save again right after that in front of the Crank-a-Kai.

6. Use the next coin to make the exclusive Yokai appear, but do not save after obtaining it. Go into your inventory and use a book to change its attitude if you wish, and once it has the desired attitude, use 5 Holy Orbs to raise its level. This raises S rank Yokai to level 44, giving you a much better view of its stats than at level 1.

7. After you have checked the Yokai's stats at level 44, if you deem it desirable, you are free to save the game and keep it. However, if it does not look like it has good stats, turn the game off and reset. You may not be able to abuse what prize you get with each coin, but you can abuse the stats of the prize you get through soft resetting, so there is no worry about Yokai stats being predetermined with your coin.

8. Repeat step 7 until you have found your desired Yokai with the desired stats, and then rinse and repeat to get the rest of the exclusive Yokai.