The end of the second mission, which features this four-man squad holding off a near unlimited army of battle droids.
Anytime that Boss (re: the Player Character) has to go solo - usually, he'll end up in solo combat with some of the tougher enemies of the game, be they Droid Dispensers, Super Battle Droids, Trandoshan Elite Mercs, or Dwarf Spider Droids, having to take them down with no backup.
As Boss and co. close in on Sun Fac, he gets in his star fighter, begins to take off and seemingly out of sheer spite, instead of just making a run for it, he decides it would be fun to hover around and take a few potshots at Delta Squad with his ship's laser cannon. However, just in the nick of time, Sev shoots down the starfighter with his sniper rifle.
Alone, outnumbered, and outgunned on a derelict republic ship, RC-38 still swiftly reacts to a Trandoshan ambush with heavy blaster fire and snark. "You lizards need to learn I'm a lot scarier than you are."
Getting to fire the main gun of an AT-TE walker.
The Deltas blowing up the Trade Federation warship during the final section set aboard the Prosecutor.
On a meta level, one of the writers of Star Wars: The Clone Wars liked Delta Squad so much that he insisted they be added to an episode, presumably so they could be confirmed for the Disney canon instead of being shunted into the Legends continuity along with the rest of the video games.