You can use rare candies to ease the process but you only have a limited supply. If you are looking to catch a lot of Pokemon or if you already have a lot of Pokemon and you want to level each of them to the max, then it will take considerable time which you may not be willing to spend.
If you want unlimited rare candies, you can use the cheat rare candy to do so. What are the Benefits of using these Codes? Pokemon Ultra Moon Cheats List Purpose & Usage
