Hi @Pedrohenrique
Usually people use the brushed motors because they provide a vast variety of gear ratios and easier to control the direction of them.
About the battery question, it depends on the motors and the amount of current drawn but it’s always better to have an extra battery in case of emergencies and because batteries could be damaged while in use specually in (sumobot fights).
i suggest that you take a look at these two discussions first.
