It's easy to tell that the Saiyans are the stars of the show in Dragon Ball games, as they have access to a host of powerups and two of them happen to be the main characters. Despite this, certain games with character creation elements have opted to let players choose from a number of races instead of just Saiyans. Dragon Ball Xenoverse is a great example of this, as it gives players a choice between five different options, but even this is somewhat lackluster given the size of Dragon Ball Super's multiverse. Thanks to the Tournament of Power arc, viewers have been introduced to a ton of new races that could work well for playable characters in the future.
Aside from vastly expanding the cosmology of Dragon Ball, Dragon Ball Super also introduces some new, powerful fighters. During the Tournament of Power, viewers get to see the ten strongest warriors from eight of the 12 universes, and some unique individuals show up. Most astounding, many of these fighters are able to stand up to the might of Super Saiyan Blue, with some even managing to surpass that power and push Goku and Vegeta to new heights. These fighters presumably aren't the only member of their capable races.
Dragon Ball Xenoverse - Playable Races
In Dragon Ball Xenoverse, players can choose between five races. The options are Earthling, Saiyan, Namekian, Majin, and Frieza Clan, all of which originate from Dragon Ball Z. The biggest problem with these options is that Saiyans are obviously the most powerful of the five, and most of the other races simply can't keep up with them. Members of the Frieza Clan can use the Golden transformation to reach god-like levels of power, and theoretically a Majin could also with enough training or absorption, but Earthlings and Namekians would never realistically stand a chance against a Super Saiyan Blue.
This isn't to say that these races aren't good choices, as both Xenoverse and the Tournament of Power give them meaningful ways to contribute, but rather to point out that there are plenty of other options that would complement these choices well. In the anime, Krillin and Piccolo are clearly at a disadvantage compared to some of their teammates by nature of their race's natural limits, but this arc places more emphasis on their skill as fighters and their strategic thinking than their raw power.
The Trio of Danger - Wolf People of Universe 9
One of the first times Dragon Ball Super shows capable combatants from a universe other than six or seven is during the exhibition to the Tournament of Power, also called the Zeno Expo. During this, viewers get to see the Trio of Danger in action. Though they are a bit over the top, they showcase some impressive power and give the Saiyans a run for their money. Admittedly, they are more of a challenge for Gohan and Piccolo, but they are unique characters nonetheless. They were also relatively popular so it would be nice to be able to create one as a playable character.
Ganos - Bird People of Universe 4
Ganos is another unique character to make an appearance in the Tournament of Power. Though he is ultimately eliminated by Master Roshi, it's made very clear that he is young and inexperienced. If Ganos were older and spent more time training and fighting powerful foes like the Z Warriors do, it seems likely that he would be capable of great things. Even during his short time in the Tournament of Power, he manages to shatter his limits several times, so this would make a great playable character race.
Of note, Ganos has a transformation, something that is key to making any playable character in Dragon Ball feel fun. It's no accident that all of Dragon Ball Z: Kakarot's playable characters have a transformation, and even Dragon Ball Xenoverse created some transformations for those races that don't have them naturally. Ganos can turn into a large, muscular bird-like form and increase his speed and power dramatically. The longer he stays in this form, the more powerful he becomes, which would make for an interesting mechanic for players to use in a Dragon Ball game.
Dyspo - Rabbit People of Universe 11
As one of the three strongest members of the Pride Troopers behind Jiren and Top, Dispo is a force to be reckoned with. What he lacks in raw power he makes up for in speed, and Dragon Ball has shown time and time again that speed is often the more valuable trait. It takes the combined might of both Frieza and Gohan in order to take Dyspo out, and he proves himself earlier in fights against Goku and others. Speed would be a primary trait for players of Dyspo's race, and with the Super Maximum Light Speed mode, they should be able to hold their own against god-like enemies.
Other Races in the Tournament of Power
These are just a few of the new alien species shown in the Tournament of Power, but there are plenty of other ones that could work if expanded on a bit. From Universe 2, the Magical Girls like Ribrianne prove to be very powerful, and that universe also has Yardrats that are capable at fighting. Universe 3 is full of robotic combatants and Universe 6 has fighters like Hit and Botamo. As it is the parallel universe to 7, it's assumed that these races also exist within Goku's universe.
Alongside the wolf people of Universe 9, there is also a breed of quick and deadly cat people and a powerful and defensive dragon person. Universe 10 has fairies, and fighters Obni and Rubalt both prove to be relatively powerful and maintain a sense of honor even during their erasure. Finally, Universe 11 features the likes of Jiren and Top, both of which could also theoretically be made into a playable race. Obviously, the Tournament of Power shows the best of the best from each universe, but it does show off what each race is capable of with enough training and dedication.