Dragon Ball Z: Kakarot will retell the legendary tale of Goku’s most iconic battles. It has been confirmed that the story won’t be a 1 to 1 recreation but include characters such as Launch and Android 13 who were stapled characters in the original Dragon Ball but rarely seen in Dragon Ball Z. In a message from the series creator, Akira Toriyama, he explained these are backstories were never told in the manga.
Source: N4G PC Dragon Ball Creator Provides Message to Fans About Dragon Ball Z: Kakarot