In The Movie, when Justin and Alex fight each other.
In Wizards Vs. Angels, when Justin and Alex fight again, while they're opposites on the scale of Good Vs. Bad, with Justin representing the evil (dark wings) and Alex the good (white wings). Some might say that they reached the Cain and Abel point successfully.
In the movie, Alex manages to get the Stone Of Dreams, then she suddenly slips and almost falls into a dark abyss, before she starts screaming Justin's name in desperation. He gets to her from the other side of the abyss almost instantly and saves her.
Also in the movie, Theresa gets one, going Mama Bear against a witch on her own. Notably because a)She's mortal, b)She doesn't even remember her kids, and c)She seems to be the only person to care about Max's disappearance.
Then, the guy the witch was using to turn back to a human stole the Stone of Dreams from her and wished her back into a parrot.
Justin's overall attitude toward Mason in Wizards Vs. Werewolves. He's glaring at him in the background and when he's the most prominent person in the shot. Don't mess with Alex's feelings. 'Cause if you do, Justin's gonna be pissed.
Doubly awesome when he prepares to throw down with Mason, despite the fact that Mason is in full wolf mode and has gone batshit crazy with rage.
And he freaking holds his own against the fully transformed damn werewolf, with some rather impressive martial arts moves. Monster Hunter training clearly did him a lot of good.
In "Wizards Vs. Everything" when Max, Alex and Justin pull a Batman Gambit on Gorog by pretending to join him, he grabs and gloats about winning, then all three Russos put their hands together and chant a spell that completely vaporizes Gorog!
"By the way, we're having dragon heart for dinner" - Let's face it, Alex throwing down with a dragon must have been really awesome.
Throughout the series, it's mentioned that the subway shop is barely getting by. In the last episode however, when everyone starts to truly work together, the restaurant becomes successful and busy, in contrast to previous comments. Just goes to show how successful they can be if the family works together.
In "My Two Harpers," Jerry wants to find a way to make extra money. He listens to Justin's binder idea, while they both don't even bother to hear Max out. Max decides to implement his idea (opening the sub shop up to the Wizard World) on his own. As Jerry and Justin marvel over the binder, Max enters and dumps a bag full of money on it.
The fight scene between Alex and herself in Alex V.S. Alex, especially near the end where Alex sacrifices her own magic to defeat and absorb Evil!Alex back into her in order to save the world.