Tear Jerker / 1 Minute Melee

• Lucario vs. Renamon starts out with Lucario visiting Sir Aaron's grave, and the battle starts due to Renamon showing up and him wanting her to leave him alone to mourn.
• While it's not made clear whether he's been killed or not immediately, Bowser catching Junior's defeated body and turning around to face Mecha Sonic in the rain at the conclusion of Bowser Jr. vs. Metal Sonic is this regardless.
• Meta Knight's death at the end of Zero vs. Meta Knight. As much as he may be disliked for being a complete Game-Breaker in Super Smash Bros Brawl, he certainly didn't deserve that. It's made even worse by the fact a massively Out of Character Zero shows no remorse whatsoever— and is in fact gleeful at having brutally murdered him— which, along with referring to Meta Knight as a "soulless copy", gives real credence to the idea that he's gone Maverick.
• On a similar note to the above, Flash's death at the end of Sonic the Hedgehog vs. The Flash. Whilst yes, he did attack Tails and Knuckles before the fight itself on the given implications that they attacked him first, it's still both chilling and sad in equal measures to see Sonic standing over his twitching corpse and casually mocking his opponent after he's just killed him. It's just so Out of Character for Sonic that he comes off as evil.

  "You deserve that for hurting my friends."

• The in-series rivalry between Akuma and Kenpachi reaches a very sobering conclusion for the both of them. Although Oni is credited with the victory, it's very much a mutually assured destruction. Kenpachi was killed by Oni's Raging Demon, but only AFTER striking two major wounds, leaving a deep gash in one of Oni's shoulders and taking one of his arms clean off. Oni can't even stand on the victory podium and falls to an uncertain fate from the blood loss after it's brought him into frame. Even if Oni survives, he's been robbed of the one thing he lives for: The ability to fight without physical or moral limitation.
• The ending of Gaara vs. Crocodile: due to Crocodile's sand manipulation and Gaara being covered in it, Crocodile manages to utterly demolish Gaara, leaving no one to save his village from being blown up.