Captain Toad
Despite their situation, Toad could barely contain his excitement. Finally, the chance to prove he was a hero. Finally, the chance to make up for his inaction 5 years ago. As the army stormed into the room, Toad reached for his bag, only to realize he was out of turnips. In a panic, he could only watch as Mario parkoured across the enemies on his way to the throne room. Then, it dawned on him. Could he...? Without even thinking, he used all of his strength to launch himself into the air and land on a Goomba, then hopped to the next one. Toad could barely hold back his grin as he leapt from enemy to enemy, a feat he had only ever dreamed of. Before he knew it, he had reached the end of a hallway, where a door labeled "Lab" stood. Looking back and seeing no one, Toad broke down the door and tackled the first thing he saw, which of course was the professor.
"I hope you're happy, betraying the kingdom by making a doomsday device!" Toad shouted, as the professor squirmed against his surprisingly strong grip.
"You don't understand! Bowser gave me no choice! It was help or die!"
"You mean you wouldn't have wanted to die for the princess? For the Mushroom Kingdom?"
"Look, Captain, I can tell you are upset. I assume you are here to interrogate me about the weakness of the staff?" At this Toad slightly loosened his grip, but not enough for the professor to escape. "I thought so. Look, I never really joined Bowser, I only agreed to make the weapon out of self-preservation. However, I made sure to study ways to combat the Star Gems, and you'll be lucky to know that I have indeed discovered and obtained just what you need."
"Then where is it?" Toad scowled. E. Gadd, with Toad still not letting go, directed Toad to a painting hanging on the wall. Removing the painting revealed a safe, and E. Gadd punched in a code to open it. Inside was a box, just too large to fit in Toad's hand. He reached to open it, but the professor shook his head.
"I wouldn't open it until you need it. After all, it's a one-time use. Now, if I were you, I would get that to Mario before he gets into too much trouble." Toad nodded, and began to run out before hearing footsteps thundering towards the door. He looked at the professor, who was moving a bookcase away from the wall, revealing a hole in the wall just large enough for Toad to crawl through. "I'll hold them off. This passage should put you just down the hall from the throne room. Now hurry!"
"Thanks. And, um, sorry about attacking you earlier." At this the professor chuckled.
"You can apologize after the kingdom is saved. Now go!" Toad dove into the hole, just as the professor covered it back up and the enemies stormed into the room.
Mario
Mario ran up his fifth flight of stairs as the sounds of battle echoed throughout the castle. He hoped the Toads had managed to figure out how to defend themselves, but for now his primary concern was reaching the throne room. As he suspected, he exited the staircase to find a long hallway with ornate doors at the end that almost certainly lead to the throne room. As he made his way down the corridor, however, he began to feel uneasy. No traps, no guards, nothing. When he was only a few feet away from the door, a familiar figure jumped from rafters.
"I've been waiting a long time for this," Bowser Jr. leered. Mario simply glared at him.
"Look, kid, I don't want to hurt you. Just-"
"Maybe not, but you do want to hurt my dad." Mario said nothing, only frowning. "Sorry, but I can't allow that to happen. For starters, you couldn't hurt him even if you tried, but I still want to stop you. Mainly because, if I can kill you, Dad will finally be proud of me. So, I hope you're ready, Mario, because this ends now!" It was only then that Mario realized Bowser Jr. had a weapon, a familiar looking paintbrush, which Jr. began to twirl rapidly. Leaping into the air, he began to turn darker before shifting into an entirely different form. Of all the things Mario had expected to encounter upon returning to the Mushroom Kingdom, Shadow Mario was not one of them. With glowing red eyes, he leapt at Mario, who barely had enough time to dodge. Theoretically, Shadow Mario's only weakness was water, but there was no water in sight, especially considering the location of the castle. As Shadow Mario prepared to dive at him again, Mario tried blocking the attack, only to get swatted to the side like a fly.
Mario knew he had to come up with something quick, or else Shadow Mario would quickly outlast him. Fortunately, he had an idea come to him. What if the water wasn't necessarily his weakness, but rather the force from F.L.U.D.D. simply knocked him over. In other words, if Mario could hit Shadow Mario with enough force, maybe he could take advantage of the moment and get the brush away from Jr. As Shadow Mario prepared to attack one final, Mario jumped over him and ground pounded, smashing Shadow Mario into the ground as the paintbrush flew across the hallway. Before Mario could get to the brush, however, the throne room doors burst open to reveal Bowser lounging on his throne, glaring at Mario.
And he was mad.