Luigi
He had done it. His flip had connected, smashing open the Smash Ball. Power beyond his imagination flowed into him, through his very veins. He liked it. He liked it a lot, and he wasn't going to waste it.
He heard a God-like voice call out, "FINISH THEM!! SHOW THEM WHAT YOU'RE MADE OF!!" Luigi fully agreed, and nodded in it's direction. It was his time to shine.
As he casually walked over to the other three, who were in a panic, he thought of how he should finish them off. That's when he saw Wario try to run over him with the "Wario Chopper".
"HOW DARE YOU!!" That's when he started it. Luigi had activated his Final Smash, the "Negative Zone". As he started to dance like a drunkard, the world around them grew very hazy. Colors were distorted, the floor twisted and turned, and they couldn't stand up if their lives depended on it. Ironically, they did.
Wario fell off his bike, Mario fell asleep instantly, and Waluigi fell flat on his face, rolling along. Luigi knew they were weak, pathetic, awaiting their fates. He made it quick.
He ran up to Waluigi and delivered a "Fire Jump Punch". Being in the "Negative Zone", Waluigi lifted off like a NASA rocket, an out of the boundaries. Next was Wario. The fat lard never could catch on that he should've kept an eye on him. He delivered another "Fire Jump Punch".
Lastly, Mario. Poor guy, he was asleep. Luigi couldn't kill him while he was sleeping. But he could kill him, and he would. He woke him up, helped him up, hugged him good-bye, and delivered his last "Fire Jump Punch". He watched as Mario flew up, up, and out of the boundaries.
"GAME!!". He couldn't believe what he just did. He not only killed off his top rival, but also his rival's brother and his own brother. As the "Negative Zone" shrunk, he sat down and cried. He vowed he would never use this move again. He couldn't, he wouldn't, bear the pain his dark side had dished out, not again.