It has been three years since the Kalos League. Alain and Mairin have travelled to Kanto, where there have met up with Ash and his new girlfriend Serena. The first thing that Ash did was treat them in his mother's restaurant, Pallet House.

"Ah, that was soooo delicious! Ash, your Mom's a really good cook!" Mairin exclaimed, rubbing her full tummy. Next to her, her Chespin cried out in agreement, rubbing his tummy with satisfaction.

"It was indeed a delightful meal." Alain said simply, but from his tone, Ash and Serena could tell that he was sincere. "Thanks a lot, guys. You've made my Mom really happy." Ash said. "So, now what do you want to do?" Serena enquired.

"I know!" Ash pumped his fist in the air excitedly. "Let's battle!"

"Pika pika!" Pikachu yelled excitedly. Serena sweatdropped. "Ash, I wasn't talking to you…"

"That's a good idea. Charizard and I have been looking forward to our rematch with you, Ash." Alain spoke, an excited grin slowly forming on his face.

The two Trainers later stood opposite each other on the battlefield in Professor Oak's house, while Serena and Mairin, along with Chespie, sat at the side. Serena drew out her Pokeballs. "Everyone, come out!" Her Delphox, Pancham, Sylveon and newly-caught Vivillion appeared in flashes of light. "Let's cheer for Ash and Alain today." Her Pokémon responded with their own cries of agreement and turned to face the battle. Pikachu was with them, perched on Serena's shoulder as he usually did with Ash. It was irrefutable proof that Ash and Serena were meant for each other.

"Charizard, come out!" Alain threw out his Pokeball, and his Charizard appeared with a roar. "So, Ash, are you going to call Greninja?"

Ash chuckled. "Not quite, Alain. You see, I have a certain Pokémon of mine who is quite eager to battle you. He's one of my oldest friends, and among my strongest. I choose you, Charizard!" Ash threw out his Pokeball, and the Fire-Type appeared, letting loose an earth-shaking roar that made everyone shield themselves from the gusts of wind that had been kicked up.

Alain stared in amazement at Ash's Charizard. It was a good bit larger than his own. He could tell from its size and musculature alone that it was easily as strong, if not stronger, than his own Charizard. Alain's Charizard also narrowed his eyes at his opponent, who was likewise eyeing him with interest. It was then that Alain noticed the Mega Stone wrapped around the neck of Ash's Charizard, by a fire-resistant orange cloth that blended in perfectly with Charizard's skin.

"So, you can Mega-Evolve your Charizard as well, huh? Is it X or Y?"

Ash smiled. "You'll see. Let's begin!"

"Go for it, Ash and Charizard!" Serena yelled, while Pikachu, Delphox, Pancham, Sylveon and Vivillion were all yelping and cheering.

"We'll take the first move! Charizard, use Flamethrower!" Alain commanded, and a torrent of flames shot out from Charizard's mouth.

"Use Flamethrower too, Charizard!" Ash yelled. His Charizard responded with an equally impressive bout of flames. The two attacks collided in mid-air, shooting flames in all directions and raising the surrounding temperature drastically. Then, too everyone's surprise (except Ash), the flames of Ash's Charizard began pushing back the flames from Alain's Charizard, until the flames collided into Charizard's body, sending up plumes of smoke.

"Charizard! You okay?" Alain shouted worriedly. As the smoke cleared, Alain's Charizard was seen staggering to his feet, roaring defiantly to Ash's Charizard, who responded with a louder, more impressive roar.

"Let's go! Respond to my heart, Key Stone! Mega-Evolve!" Alain tapped his new Key Stone, which glowed along with the Mega Stone around his Charizard's neck. Golden tendrils of light connected the two stones, enveloping the Fire-Type Pokémon in a myriad of colored light. When the light subsided, Mega Charizard X, with its signature black and blue body, stood in his place, letting off a fearsome growl.

"I've been waiting for this. Charizard, we'll show them our full power! Mega-Evolve!" Ash cried out, tapping the Key Stone from the bracelet on his hand. Golden tendrils of light connecting the two stones were likewise followed by Ash's Charizard being enveloped in a shower of light, before its Mega-Evolved form stood in its place.

Alain and Mega Charizard X gaped in shock. This was neither Mega Charizard X nor Y. In fact, it looked like a fusion of both. The Charizard now had a similar black body, but its underbelly was orange with blue and yellow stripes at its center. Three spikes, so reminiscent of Mega Charizard Y grew on its head, but at the sides of its mouth were ever-burning flames, as well as from the spikes that had grown from its wrists. This was Mega Charizard Z, the first of a new type of Mega Evolution.

"Meet Mega Charizard Z." Ash said, gesturing proudly. "Incredible…I've never seen anything like it before. How did you find a completely new Charizardite?" Alain exclaimed. Ash scratched his head embarrassedly. "Well, you see, it's a really long story. But essentially, Charizardite X and Charizardite Y were fused together to form the new Charizardite Z. Which means…" Ash tapped his Mega Charizard Z proudly, "Mega Charizard Z gains both X and Y's abilities, Tough Claws and Drought."

As if to prove his point, the sun suddenly seemed to shine brighter, and the surrounding temperature became noticeably hotter.

"Let's continue! Charizard, Mega Punch!" Mega Charizard Z flew up and made a beeline towards Mega Charizard X. Before Alain even had time to react, Mega Charizard Z had socked his opponent cleanly in the jaw, sending him reeling and wincing in pain. "He's fast," Alain thought to himself.

"Use Dragon Claw!" Green, shadow-like claws projected from Mega Charizard X's claws, as he flew towards his opponent. "Dodge it!" Ash commanded. His Mega Charizard Z flew up, using its wings to swerve and turn as Mega Charizard X slashed at it frantically, but Mega Charizard Z merely dodged them all, almost lazily. "Now, use Mega Punch!" Mega Charizard Z struck out with a massive, glowing fist and slammed it into Mega Charizard X's belly, sending his opponent flying backwards.

"Now press them with Dragon Claw!" Ash commanded, and green shadow-like claws likewise were projected onto Mega Charizard Z's claws. Mega Charizard Z struck Mega Charizard X while it was still dazed, each strike stronger and more painful than the last, until a powerful swipe across the face sent Mega Charizard X crashing to the floor.

Alain gritted his teeth. His opponent was a lot stronger than he'd anticipated.

"Fire Blast!" Ash yelled, and golden-orange flames in the shape of a kanji shot out of Mega Charizard Z's mouth, hitting his opponent who had just gotten to his feet. The power of the blast knocked Mega Charizard X further back, and Alain could tell that his partner had taken a lot of damage already, as could be seen from the scratches and bruises on his body. Despite this, Alain felt his body pulse and throb with excitement. He could always count on Ash to give him an exciting battle, and this time he didn't disappoint.

Mega Charizard X growled in defiance and made eye contact with his Trainer, signifying he was ready to continue. Alain grinned. "Let's go, Charizard! Thunder Punch!" Yellow tendrils of electricity enveloped Mega Charizard X's fist as he struck out at Mega Charizard Z, hitting him square in the chest. Mega Charizard Z winced as the blow sent him skidding back across the battlefield, but recovered almost instantly, and roared back at his opponent.

"Finish this! Blast Burn!" Alain's Charizard flew into the air, enveloping himself in raging, sapphire flames before smashing his fists into the ground with all his strength, sending an inferno of massive blazing shockwaves careening towards Mega Charizard Z. An explosion of fire and smoke spiraled out of control into the air above as the attack connected.

"Did we win?" Alain peered through the column of smoke, but could make out no sign of his opponent. The moment seemed to stretch on for eternity, never-ending, never-stopping, until…the smoke finally cleared and Alain rubbed his eyes to ensure that what he was seeing in front of him was real.

Mega Charizard Z stood upright on the battlefield. He was covered in cuts and bruises, and was taking in labored breaths. But incredibly, astoundingly, he was still alive and well. "You alright, Charizard?" Ash asked, concernedly. In response, Mega Charizard Z let loose another earth-shaking roar, sending shockwaves that forced Alain and Mega Charizard X to cover their eyes from the wind and sand. "Unbelievable…Ash's Charizard has such stamina…" Alain thought to himself.

"Now it's our turn! Use Fire Blast, then follow up with Dragon Tail!" Mega Charizard Z roared in agreement, before letting loose the powerful Fire-Type attack, hitting Mega Charizard X square in the torso. Not giving his opponent a chance to recover, Mega Charizard Z flew up and brought his tail, now covered in a green aura, and slammed it down, sending up plumes of dust and sand.

When the dust cleared, Ash and Alain gaped at the sight. Both Mega Charizards were still standing, never taking their eyes of each other, eyeing each other warily and anticipating the next move. "Thunder Punch!" Crackling with electricity, Mega Charizard X launched his fist towards his opponent.

"Charizard, dodge it then finish up with Seismic Toss." Ash answered smoothly, folding his arms and looking smug. Mega Charizard Z swerved and turned, easily avoiding Mega Charizard X's punches. He then wrapped his arms around his opponent, before spreading his wings and took the air. Alain could only watch on helplessly as Mega Charizard Z began to do loops in the air, while Mega Charizard X began to see stars, dizzy after doing so many turns. Mega Charizard Z roared as he dove headfirst into the field, causing the field to shake and chunks of the ground to thrown up in large, boulder formations.

As the dust finally cleared, Mega Charizard Z stood breathing heavily, standing over an unconscious Mega Charizard X, who had reverted back to his original form. Standing up to its full height, Mega Charizard Z bellowed loudly for anyone in the surroundings, proclaiming his strength and let loose a bout of flames periodically. In a flash of light, Mega Charizard Z had reverted back to his base form as well.

Alain helped his Charizard to his feet, patting its head affectionately. He always took his losses well, and, as could be seen from the smile on his face, he was satisfied with the battle even though he had lost. Ash was also patting his Charizard on the back. Serena, Mairin and the other Pokémon had run over as well to join them. "That was amazing, Ash! I knew you would win!" Serena said with a light blush on her face. "Pika pika!" Pikachu chirped in enthusiastically.

Charizard let out an indignant huff. Serena giggled and said, "Alright Charizard you were wonderful as well." Charizard puffed out his chest and huffed, a smug look on his face. "Indeed, Charizard, you never fail to amaze me." Ash said.

"Your Charizard is strong, Ash." Ash turned to see Alain and Mairin walking over with Alain's Charizard. "Thank you for an exciting battle."

"It was my pleasure, Alain. I enjoyed the battle too." Ash smiled as the two shook hands. Behind them, the Charizards fist-bumped each other as they exchanged amicable growls. Ash went over to his Charizard and put his hand on his chest. "My Charizard and I have gone way back, and he's always proven himself my strongest Pokémon, even matching that of Greninja. He's my irreplaceable Charizard." As if on cue, Charizard blew a torrent of flames into Ash's face.

"Still as strong as ever," Ash muttered, his face black with soot, as everyone around him began laughing.