Here's how Brian and Sunset Shimmer join the fight in Revenge of the Red Diesel.

[we sideswipe back to Kamino where we see the battle is still raging on, and we aslo see that Skystar has engaged Novo]

Princess Skystar: Mother, stop! It's me! Skystar, your daughter!

Queen Novo (darker voice): Then she can be my little inquisitor!

Princess Skystar:

Queen Novo (darker voice): Deal with it! [force pushes her back]

Princess Skystar:

[they firously clash sabers, as the other continues battling the clones]

[Soon, Brian, Sunset, and K2 arrive]

Brian: Whoa!

Sunset Shimmer: [hands K-2 a blaster pistol] You'll need this.

K-2SO: My goodness! Shut me down!

[then Hiro's shuttle lands]

Princess Luna: Surprise!

Brian: Luna, Hiro!

Hiro: You really think we wouldn't join in this battle. In a situation like this, it involves every single member of the Republic.

Princess Luna: Now, let's destroy these clones!

Brian: Right! [ignites his Lightsaber]

[They charge strait forward as it cuts back to Coruscant]