I think I described Mimiku's attack shadow sneak wrong. But hear me out here. We never see Mimikyu use shadow sneak in the Anime. So I took some creative license there. Think of it like it sounds. Mimikyu extends it's shadow and sneaks up on the target sorta...

The light hurt, and that's what caused him to wake suddenly from the dream he'd been having of flying through the air. Strange things stood in front of him, and he looked at them, confused. Where was he? for that matter, what was he? He heard voices from the beings that stood in front of him, but they weren't talking. He realized he was reading their thoughts.

'Mewtwo, my greatest achievement.'

'is that me?' It was all too much and he closed his eyes, falling into a deep slumber.

"Finally Mount Moon!" Ash said happily, "I can't wait to get to Cerulean City for my next badge!"

"Are you sure you want to go to Cerulean?" Misty asked, looking unhappy

"Look if this is about you being the Cerulean City Gym leader, then I can skip you and come back to challenge you when you are ready."

Misty looked grateful, then thoughtful, "That's nice of you to offer Ash, but as a gym leader, I cannot turn down a challenger, even if it means I have to go back to the gym, and," she shuddered, "My sisters."

"What could possibly be so bad about sisters?"

"Let's just say we have a difference in opinion on pretty much life in general and leave it at that."

"Well as long as you are sure?"

"Yeah, lets get going so I can get this over with."

Then as they were coming to the entrance of Mount Moon a man came stumbling out, chased by Zubats. Ash had Mimikyu thunderbolt them. One fell to the ground and the rest scattered into the sky.

"Oh thank you. Those Zubat have been chasing me all around!"

"Who are you?" Ash asked

"Me? I'm Seymour. Seymour the scientist. I'm here looking for the mysterious moon stone."

"Moon stone?"

"Yes the moon stone. You see I believe that Pokémon all came from the stars and that the rocket they used to get to Earth is the moon stone. But to prove my theory I have to find it. Things were going fine until those Zubat suddenly attacked me for no reason!"

"Zubat normally leave travelers alone unless they are hungry," Brock said, "Or if someone attacked them."

"I would never! I don't even have a Pokémon with me!"

"You may not have, but didn't you notice these lights here? Someone has been messing with the Zubat's environment. They must have awoken and having seen you thought that you did it."

"Then we'd better find out what's going on so we can stop it," Ash said, leading the way into the cave.

It didn't take them long before they found the rockets bragging about taking the moonstone to their boss.

"It's that same lady that Mimikyu fried back at the Pokemon Center," Ash whispered to his companions, "But they've brought reinforcements this time."

And indeed they had, the red-haired rocket Ash and her blue-haired friend were bossing around a group of other rocket members,

"We need a plan. I don't thing the four of us can take on that many rockets."

Before they could do anything though, a group of Clefairy came pouring out from wherever they had been hiding and surrounded the rockets, waving their fingers back and forth rhythmically until Ash saw their eyes glow as a group,

"They're using Psychic! Let's help them out! Mimikyu thunderbolt!"

The rockets panicked as the group were lifted into the air and the thunderbolt coursed through them, and then they were dropped rather forcefully by the group of clefairy. Ash noticed however, that the red-haired rocket and her blue-haired teammate were no where to be seen. The clefairy in charge wagged its finger again and teleported away with the rockets in tow, only coming back once they were all gone from the cave. The lead Clefairy stepped boldly up to Ash, looking him dead in the eyes, and seeming to come to some sort of decision, for the next thing he knew, a very small looking Clefairy stepped out from the group and pointed at Ash's Pokebelt.

"You want to come with me?" He asked, awed, as the Clefairy nodded, but before it walked over it touched the moonstone, evolving into a Clefable. Then it came to him, and without a struggle, was caught.

Then the leader of the Clefairy started a song that thrummed with power, as he lead a strange dance around the moonstone. Ash watched, amazed as they danced in and out of the circle, when as if by prior agreement, a few of the Clefairy danced out of the circle, and touched the stone, including the lead Clefairy, all becoming Clefable. Then they pushed all together, getting the moonstone rolling until Ash could no longer see it. The lead Clefable sang again, and the Clefairy and Clefable all left the clearing as suddenly as they had appeared.

"Hey, Wait for me!" Seymour yelled as he tried to follow, "Thanks for your help guys but if I'm ever to prove my theories about Cleafairy then I need to stay with them."

Ash nodded as Seymour took off down further into the cave. Nothing much else happened in the cave other than Ash finding a TM for water gun on the floor and battling a weird man when they had almost come to the exit and had spotted two fossils and the man had challenged him for them. coming out of the cave, he noticed Misty looking even more down.

"Hey Misty, like I said before, if you really don't feel up to this then I'll skip you for now."

"Thanks again Ash, but I need to face my sisters, if only to show them I"m not the same person that can be bullied by them anymore."

Ash nodded, and they all walked into Cerulean together.

End chapter

So not much changed other than describing how Ash will have a Clefable now.

Clefable: Sing, Metronome, Magical leaf, Double-Slap, Dream Eater (egg move, not unlocked)