Steven's intro and outro to Oni are heartbreaking, as the beast who once was Akuma proves impossible for even the Half-Gem to redeem, you could almost sense the despair in his words:
Steven Universe: Oh no... Why? Just... Why? Steven Universe: I can't save you... Your totally gone...
Many of Lucy's quotes are sad too. She rejects the thought of redemption from the X-Men, Superman, Sora, Steven and Raven and is filled with so much hate and contempt for her opponents..
Vs X-Men intro: It's too late for me.
Lord Raiden laments at what has become to former Queen of Edenia:
Vs Sindel intro: Once you were a fair queen. Now you're a sadistic puppeteer.
Scarlet Witch's Rival cutscene breaking down into tears while Zatanna's comforting her. After all she's been through in both the comics and the movies the poor girl has been through so much. Eventually becomes a heartwarming moment when Zatanna refers to her as a person. It must have meant a lot to her.
A lot of intro quotes to Phoenix are either horrified or pitying Jean, but Cable's?
Cable: "Sorry, 'mom'... I gotta do what I've gotta do."
Endings
Ace and Jiraiya's endings both have them surrendering themselves to death once more, sending a final message to Luffy and Naruto respectively. This can also count as Heartwarming Moments.
The Blue Team's ending reveals that Tex was not allowed to return with them, something that Church is saddened by.
Lucy's ending has her deciding to remain all alone in the world of Death Battle to protect others from her bloodlust.
In Hulk's ending, he is trapped in eternal battle with Doomsday.
Even though he's a Supe with very little regard for collateral damage and an all-around asshole, one cannot help but pity A-Train in his ending. When Compound V wasn't doing it for him, he mixed it with Bane's Venom, and the resulting drug cocktail had rendered him bound for a wheelchair for life. Soon after, another speedster takes his spot. The last words really drive the point home.
"His unhealthy life choices had finally caught up to him. Now, life as he knew it was over."
Likewise, Homelander may be despised by almost all of the cast for very good reasons, but his ending has him use his newfound power to destroy Vought and take over the world... at the cost of his reputation that he so desired to uphold. He pretends to act as the hate and fear doesn't bother him, but deep inside, he wants to be seen as a hero again.
