In order to win battles, you really have to consider the Types (colors) of your characters and opponents so you can deal extra damage and reduce incoming damage. There are two scenarios where you need to consider the color/type composition of your team. The first one is the normal map clearing composition. This should be composed of characters with different types since you don't have control of the enemy types you'll encounter along the way.
Note: You can't have similar characters in the team. That means you can't have a Kaioken Goku and Super Saiyan Goku in the same team. The only exception here is the Friend or guest character you can invite. This rule doesn't apply to them.
The second one is the anti-boss composition. If you know the boss's type at the end of the boss map, customize your party with the best characters who strong against the boss's type as the core. Choosing a guest/friend character that is strong against the boss will help a lot as well. Also, don't bring characters that are weak against the boss. That way, you'll just need to endure normal and reduced damage from the boss attacks.