Just after the fight with Plotz and Ralph before the bridge. Everyone is safe and Dr. Scratchensniff gives the others some of accidentally modified elixir to everybody, and everyone reconciles with each other (no doubt all of them feeling pretty bad for their earlier selfishness). Wakko even helps Plotz by giving the unconscious man some of the now delicious elixir.
To elaborate, Slappy got a new supply of food, and Skippy gets friends his own age.
Mindy finally called her mother "mom", and Buttons got a big plate of steaks as a reward for bringing her home safely.
Rita and Runt FINALLY find a home with Dr. Scratchensniff who also got his elixir right, and Hello Nurse, who becomes a great marketing executive, being respected for her mind instead of just her looks.
Yakko, Wakko and Dot discover their truly royal heritage, and become kings and queens.
Even Plotz and Ralph, set up as villains early on, but goes through a Heel-Face Turn get their wish, as they start up a hugely successfull burger chain, giving them money and power. Well, Plotz did, Ralph already had his wish of being a constable, so he's just given the job of directing traffic.
Their reactions when Salazar orders them to kill The Warners. As much as they were acting like the bastards they were in the beginning, the thought of outright assassinating children absolutely horrified them. The looks on their faces just screamed that they did not want to go that far.
Yakko's bedtime story to Dot.
Wakko's "Wishing Star" song.
The Wheel of Morality actually gives us a heartwarming moral.