The easiest method is to purchase characters from the in-game shop, located in the Shop & Customize section of the main menu. But don’t worry, there are no microtransactions here as everything is purchased with the Zeni currency you earn through battles.
Aside from the fact that you have to collect a lot of Zeni to acquire the characters, there is another important catch: First of all, not all characters are listed here. The shop will be updated with new items as you increase your player level, and this includes new characters. Every unlockable fighter should be available in the shop once you reach player level 20
One of the quickest ways to increase your player level is to make a wish by using a Shenron summon. This got me to level 8 and updated the shop quite a bit. You can also wish this with a Super Shenron Summon for an even bigger boost, but there is arguably a better use for this dragon, which I will discuss soon.
I would also like to emphasize again that although you can buy all of them in the shop, there is always an alternative. Aside from the eventual DLC characters and Goku (Mini), the latter of which is exclusive to the pre-order bundle, you can unlock all of them in other ways.
