A supreme double merge flavor of Awesome and Heartwarming, combined in a single blow charged with the Power of Love. In the finale, when Domon's girlfriend Rain had been captured and brainwashed by the Devil Gundam, Allenby pulls an I Want My Beloved to Be Happy, and tells Domon "Go after her. Or I'll never fall in love with anyone else Domon, but you," He then breaks into a heartwarming speech to Rain, telling her that he never blamed her for his troubles, and that their year together was more than just the two of them working together. He then finally gets to tell her exactly how he feels about her. With his feelings professed, and together at last, they pour their hearts into a large, awesome Burning Love Sekiha Tenkyoken that saves the universe.
Don't forget Domon's reunion with his Disappeared Dad, or more exactly, his recently defrosted dad. Dr. Kasshu explains to him what has been going on with the newly evolved Devil Gundam and what he has to do to stop it and save Rain, but right before Domon leaves, Raizou stops and tells Domon "You've grown, my son. I'm So Proud of You". Domon then smiles and thanks his dad, promising to return before taking off.
After being forced to fight the other members of the Shuffle Alliance, Argo declares that he will fight by Domon's side and Domon himself says they're all back together again.
Just before his final match with Domon, Sai Saici finds a letter that makes him stop goofing off and put everything into his training, to the confusion of his guardians. Turns out the letter was from his late father, lamenting his inability to restore the Shaolin Temple and asking Suisen and Keiun to raise Sai Saici. Sai Saici risks death so that the Emperor will grant his request to restore the temple and fulfill his father's dream.
It's heartwarming that the Neo France government chose George to represent them in the Gundam fight instead of Mirabeau, as even though Mirabeau was more effective thanks to having no lines he wouldn't cross, fighting fair meant more to the government than winning.
In one of the later episodes, before a pivotal match, Natasha dresses up and treats Argo to a private high-class dinner, revealing for the first time how much she hates how her government held his crew hostage and forced him to fight, and that she actually does care for him, saying that when it's all over she may just join him on that pirate crew of his.
And then she makes good on that promise, releasing Argo from his shackles and bomb and declaring she will become a pirate with him.
One more for the finale; by the end of the series, each member of the Shuffle Alliance is seen with together with the people they love and care for the most as well: Chibodee is with his Four-Girl Ensemble, George is with Maria and Raymond, Sai is with Keiun and Suizen (and a bonus photo of Cecile), and Argo is with Natasha..
Chibodee's girl group singing to him to help him get over his crippling fear of clowns while fighting the Jester Gundam. It makes him realize that they've become his new family since he lost his mother, and that he's no longer alone.
In the Japanese version they're simply singing the show's ending theme, in the English dub they're singing America The Beautiful.
The entire final battle with Master Asia. Domon finally realizes how badly Master Asia is hurting, even if his actions were wrong, and spends the fight trying to convince Master Asia to stop. When Domon lands his Finishing Move, Master Asia congratulates him on being a worthy successor. As he dies in Domon's arms, he finally apologizes for his misguided actions and reconciles with his student, and passes away after a final cry of "Look! The East is burning red!" Many Manly Tears have been shed because of this, but it doesn't stop being touching.
Adding up to the heartwarmer is that while apologizing, Master Asia opens his shirt and reveales his bare chest, clean and with no traces of Devil Gundam Cells at all, meaning that he never stooped so low, unlike certain others, he's still a honorable fighter throughout his life despite his misguided actions.
God Gundam when it is first used. The dramatic scene, how God Gundam holds Shining Gundam like a dead princess, Rain telling Domon to go to Hong Kong, it seems more like the gundams are people than mechas. Especially the tearjerking, "Good bye, Shining Gundam.".
And then we have the end of the episode that comes after this. Domon manages to arrive at Hong Kong despite being attacked by Master Asia (and saved by Schwarz) as well as by then nameless mobile suits — with one second to spare. Rain, who has been worried sick for Domon and unable to help him further, runs to the dude and goes Tsundere, calling him an idiot and then sobbing against his chest. Domon then tells her "I'm sorry for making you wait, Rain" in an unusually tender voice, and as they look into each others's eyes, fireworks go off on the background.
Before what Chibodee and George believe to be a suicide mission to finish off the Grand Gundam, the two share a drink. Not with each other, but their gundams. Chibodee pours liqueur out on Gundam Maxter while George sprays the Gundam Rose with champagne. This moment between the two is pretty touching, especially the Not So Different parallels between the duo.