I can imagine everyone is waiting for the bots to appear. Well, don't worry, I'm getting to that part.
"I can't wait to see my kids and wife again!" said Bowser as he was walking back to Castle Koopa.
It had been three weeks now since Bowser had been put in the hospital, but he was back and still bad now he was out.
Bowser walked up to the castle and was heartily greeted by the guards. "Welcome back, Your Highness!" said a Hammer Brother.
"We've missed your sinisterness, your... Sinisterness," said a Boomerang Brother.
Bowser smiled. "Good. Now, to see my wife and kids."
"Actually, we are under orders by Prince Lemmy Koopa to not let you in," said the Hammer Brother.
"The compact prince says there is a surprise for you!" said the Boomerang Brother.
Bowser shrugged and sat down on the dirt.
"I wonder what Lemmy has in store for me..." thought Bowser. Bowser heard a motor start, and turned to the side of the castle.
Approaching him was a person on a black motorcycle; a person in a blue, fairly large go kart; a silver Pontiac Solstice; a green Saleen Mustang; a souped up black Corvette; a white pickup truck; and a school bus for handycapped people.
Bowser stared at the vehicles, and merely said. "Who are you?"
At this the bus split in two halves and the halves transformed into 12'3" robots. They were both big and yellow, but one was slim, the other bulky. The arm of the slim yellow bot's left arm transformed into a large, oddly designed gun.
"You feelin lucky, punk?" asked the slim yellow bot.
Bowser stared in awe at the two humongous robots.
"Put the plasma cannon away," said the bulkier of the two.
"Aw, relax," said the slim one. "I was just playing."
At this the other vehicles transformed into robots as well.
"Impressive, yes?" said a tall, thin white bot. "We've worked our hearts out on these gargantuan mechanical structures."
"Nobody's gonna make fun of me for being small now!" said a comparatively small bot that was blue.
Bowser stared at the two robots who had just spoken. "Iggy? Lemmy?"
"How'd ya know it was us?" asked the small blue bot that contained Lemmy.
"Well, Iggy is the only Koopa I know who'd brag about the effort they put into a robot, and Lemmy... even as an 8'6" robot, you're still smaller than me."
"Aww..." said the small blue bot.
"I wouldn't say bragging... I'd prefer, expressing my exuberance over the completion of the robots," said the tall, white, slim robot containing Iggy.
"Showoff…" muttered a short and stocky silver bot that contained Morton.
"You surprised?" asked the big black robot containing Roy.
"Very..." said Bowser, who was staring at his kids.
"Good!" said a green robot that contained Wendy.
"We plan on launching an attack on the Mushroom Kingdom as these babies," said Roy.
"Yeah!" said another comparatively small robot that was black and held Junior inside. "We sneak in as vehicles..."
"And since it's the Mario and Luigi Fstival over in the Mushroom Kngdom, e'll be perfectly disguised,” said Ludwig.
"Then, we blow the place to bits!" exclaimed Larry.
"And since we destroyed the Super Scope, Mario can't beat us this time!" said Iggy.
A tear streamed down Bowser's cheek as he stared at his kids.
"Dad, you ok?" asked Ludwig.
"I'm fine, it's just... I can't believe my kids came up with such a flawless plan!" Bowser said joyfully.
The Koopalings were all smiling inside their robots, when Clawdia rushed in.
The two Koopas kissed, the other Koopalings watching.
"It's good to have you back, dear," said Clawdia.
Bowser smiled, but realized that Clawdia wasn't asking about the robots. "Did you know Iggy built these robots?"
"WE HELPED!" yelled the other Koopalings.
"I didn't want them to but Lemmy and Morton convinced me," said Clawdia.
"Morty?" said Larry and Ludwig at the same time.
"Say, don't we have a Kingdom to destroy?!" said Morton quickly, transforming back into the Pontiac Solstice.
"That's right!" said Bowser. "Go out there and kick some butt!"
"We won't fail you this time, Dad!" said Junior.
The others transformed into vehicles and drove out, determined not to fail their mission.
Bowser Jr. was probably the most determined to impress his father, but he remembered something that could be a bit of a problem...
... He had forgotten to tell his siblings about E. Gadd's robot.
"Umm... You guys..." said Junior nervously, riding on his motorcycle.
"Yeah?" said the "twins" from inside the bus.
"I forgot to mention one of my findings in E. Gadd's house..."
"Wuzzat?" asked Roy, who was driving the Corvette.
"... E. Gadd built a giant robot, too..."
At this, all of the robots transformed.
"Say what?!" asked Lemmy.
"I forgot that E.Gadd built Mario a giant robot too!" Junior said nervously.
Morton's right robotic arm transformed into a Bullet Bill launcher that at Junior, hitting his bot square in the chest. Junior was sent flying backwards.
"HEY! " screamed Bowser Jr.
Junior reached behind his back, where his war hammer was held. He pulled it out, ran at Morton, and swung. The blow hit Morton's bot in the face.
"JuNIOr you *BZZZT* iDIOt!" Morton yelled, getting back up. Morton, horrified, said, "WHAT'S *BZZZT* wRONG wi*BZZZT*th my bot's VoICe?!"
Iggy stared at Morton's bot, inspecting it.
"Well, I installed microphones in the robot's cockpit, where you are, Morton. Junior hit your bot in the face, the same place where the amplifier is held, causing the bot's electro-acoustic transducers to malfunction."
"In English?" said Wendy.
"Junior hit Morton's bot in the face, causing the bot's mic and amp to screw up," said Iggy.
"I'LL Kill *BZZZT* yO*BZZZT*u Junio*BZZZT*R!" yelled Morton.
Lemmy fired a goo ball at Morton's feet, sticking him to the position he was in. This caused Morton to trip when he tried to run at Junior.
"Hello? We have a kingdom to destroy if you don't mind!" said Roy.
"Roy is right," said Iggy. "Giant robot or not, we can't let our father down."
Lemmy unstuck Morton, and all the bots transformed and drove away to the Mushroom Kingdom, where they would finally succeed.
Or so they hoped.