Vince, Spinelli, Gretchen, and Mikey getting the entire playground to help them break T.J. out of detention in "The Break In"
In "The New Kid": T.J. getting the rest of the gang to get the rest of the student body to stop calling Gus "New Kid" when he first moves to town, and making him feel welcome. Doubles as a Crowning Moment of Heartwarming.
And in the same episode after that, Gus standing up to King Bob to get his name back.
Afer beating up Gus in "Gus's Last Stand", Gelman is confronted by the main six defending him, and he threatens to beat them up. The rest of the playground tell him that if he attacks the gang, they have to attack them as well.
Gus, a.k.a. El Diablo, beating Lawson's whole team at dodgeball single-handedly in "Dodgeball City"
Tubby finishing the Kindergarten Derby for Mikey in "Kindergarten Derby".
And he tells off the Kindergaten Derby and delivers a speech that make sure it never happens again.
Tubby being perfectly happy to just finish the race. Right up until Mikey says "Win win win!". Cue some awesome running.
In Recess: All Growed Down during the kindergarten flashback, Gus stands up to Randall, and gets the kindergarteners to start acting like they usually do in the series, showing how the kids became who they were in the TV series. After Randall gets Gus in the principal's office, T.J. assumed leader position after being a Shrinking Violet most of the time, makes his first big speech, and for the first time, turns his baseball hat backwards and says his catchphrase for the first time.
Vince: That's a great plan, Theodore!
T.J.: The name's T.J. now, Vince. (Turns his hat backwards) Now who's with me?