Dragon Ball Heroes, the most "ambitious" of the popular Dragon Ball properties, is known for some unique character transformations that didn't appear in the main series. Various Saiyans getting Super Saiyan 3 and 4 forms, on top of other power-ups for series and movie villains, created some stellar cards for the Heroes arcade game and provided the series' manga adaptation some much-needed content.
These five forms, unique to the Dragon Ball Heroes property, stand out as the best in our eyes -- whether they've given beloved characters some respect or are just flat out cool.
Super Saiyan God Xeno Trunks
Xeno Trunks, not to be confused with Trunks or Future Trunks, serves as the series' guardian of sorts -- a character who aides the player with combat skills or background knowledge of prior events that would be of interest to players as they traverse the Heroes story. He mirrors this role in the manga, where he serves as a mentor to Beat, the equivalent to the player character in the Heroes arcade games.
As a member of the Time Patrol, it's Xeno Trunks' job to ensure the timeline isn't altered by villains such as Mechikabura, Towa and Mira, who seek to alter the timeline to serve their own devious plans. In a battle between Mechibakura and Fin, Xeno Trunks achieves Super Saiyan God form thanks to his fallen Saiyan comrades giving their strength to him in order to vanquish their foes once and for all.
Fans of the series were overjoyed to see Trunks achieve such a form, especially since in his most recent mainline series appearance, Dragon Ball Super, he gets close to divine power thanks to his Spirit Sword technique -- but only ever feels the power when Vegeta, powered by God ki, dominates him during their sparring session.
Ultra Instinct Goku - Grand Priest Attire
During the Universal Conflict saga, the Xeno Warriors are faced with an astoundingly powerful foe in Hearts, the leader of the Core Area Warriors, a group of nefarious individuals who want to destroy Zeno. The Xeno Warriors are pushed to their limits and are saved by a returning Goku, dressed in the Grand Priest's regalia, his eyes silvered with the power of Ultra Instinct.
For fans of the Dragon Ball Super manga, this form is achieved differently, but in Heroes, Goku trains with the Grand Priest himself in order to fully master Ultra Instinct. While this form ultimately doesn't finish Hearts for good, Goku is still able to dispatch Hearts' minions (and look awesome while doing so.)
Masked Saiyans
The mysterious Masked Saiyan is one of the first villains shown in the Dragon Ball Heroes series. Under the control of Towa and Mira, the Masked Saiyan provides a challenge even for Xeno Trunks in his Super Saiyan form. Trunks is eventually able to overpower the Masked Saiyan and free him from Towa's grasp, revealing it to be Bardock, Goku's father, under the mask. Xeno Bardock then joins Xeno Trunks to temporarily hold off Towa and Mira.
Other Masked Saiyans appear throughout the series as Towa captures more Saiyans and mind controls them -- the Dark Masked King, Dark Broly and the Black Masked Saiyan. The former is revealed to be King Vegeta and the latter is Xeno Vegeta. While we've seen plenty of Vegeta throughout the mainline Dragon Ball series, it's nice to see underutilized characters like Bardock and King Vegeta get their time to shine in the Heroes series, especially Bardock, who manages to achieve both Super Saiyan 3 and Super Saiyan 4 forms. It's all thanks to the power of those dark masks.
Xeno Adult Gotenks
An adult form of Gotenks is something we'll probably never see in the main series Dragon Ball show, so his appearance in the Heroes media is a welcome addition. In Dragon Ball GT, Trunks served as the main character, but Goten was mostly forgotten. In the Dragon Ball Super timeline, Goten and Trunks haven't shown any physical growth since the end of Dragon Ball Z and show no signs of maturing.
Heroes just might be our only chance to see an adult version of Gotenks, where Xeno Trunks and Xeno Gotenks fuse in order to battle Baby Hatchiyack in the early days of the Heroes story. The fused fighter achieves both Super Saiyan and Super Saiyan 3 forms in Heroes but hasn't managed to hit Super Saiyan 4 yet.
All The New Super Saiyan 4 Forms
We touched on this a little earlier, but man does Dragon Ball Heroes give out Super Saiyan 4 forms like convention swag bags. Just about every Saiyan you can possibly think of achieves Super Saiyan 4 at least once in the series: Goku, Vegeta, (who combine to form both SS4 Gogeta AND Vegito,) Broly, Bardock and Gohan. (Trunks was originally supposed to achieve Super Saiyan 4 form but the series creators ultimately pivoted to the above Super Saiyan God form.)
To be fair, though, Super Saiyan 4 is probably the best thing to come out of the Dragon Ball GT series. Its combination of the Saiyan's ape origin and the Super Saiyan power-up created an iconic look that has transcended GT's mediocrity and became a beloved form to fans of the series. Xeno Goku, Xeno Vegeta and Xeno Gogeta retain their GT appearances in Heroes while Xeno Gohan gives life to those old Dragon Ball AF fan arts we all thought were real back in the early 2000s.
Heroes also treats us to additional Super Full Power Saiyan 4 transformations and a new, exclusive form for Super Full Power Saiyan 4 called "Limitbreaker," which gives the users a fiery, rose-colored aura akin to Goku Black's Super Saiyan Rose.