"Greninja, get ready and charizard use flamethrower"

They did as they were told.

Charizard managed to deal some damage whilst Greninja prepared for what ever Ash was up too!

"Now, night slash and hang onto buzzwole's leg"

Greninja summoned blades of darkness and slashed buzzwole. Then, it hang on to one of its eight legs!(I think buzzwole has eight legs as it's lower body is like a spider.)

Buzzwole tried to shake it off. 

It couldn't.

Buzzwole groaned angrily

"Buzzzzzzzz woleeeeeeee buzzzzzzzz"

"Charizard, blast burn"

Charizard started to use its most powerful move. It let out a shriek before starting to form a huge red ball of flaming gas in its mouth.

It got bigger and bigger.

Then, it exploded and a beam of ferocious, nearly blue flames shot out of its mouth!

Buzzwole was caught in the flames and burned by the super effective move!

"Greninja, Ice beam"

It worked and buzzwole fell to the ground, frozen yet burned.

Ash knew buzzwole was being hurt by its burn but is frozen and couldn't move.

Ash knew the right movement of a flamethrower to break the ice and throw a beast ball should end the battle!

Then, there was a sound of ice cracking and buzzwole broke out.

How?

Ash didn't know.

Then it fled.

Ash wouldn't let it run far though. He tode on Charizard and chased it before throwing a beast ball.

The beast ball fell...

Greninja caught it before it hit the ground.

The ball shook.

Once... twice...

Ash held his breath...

Then, it shook once more and stars appeared on top of it!

"Yessssssssss" Ash shouted and jumped.

He did a fist pump and hugged Charizard and Greninja. He thanked them!

"One down, loads to go"

Ash celebrated.

He was sure buzzwole would be a good member of his team!

 (Time skip the next day)

Ash heard his door bell ring.

Then, a post man appeared and his pidgey handed Ash a letter. Then they ran.

"Wait, you look familiar, are you Brock? If you are, then..."

Then there was a close up view of a steelix and Ash fainted.

Inside, Ash knew it is Brock! He knew the traitors must be up to something...

Deep in Adh's dreams, Ash heard a voice. 

"Arceus?"

"Yes! Ash, be careful, you need to ..."

"Arceus, what's wrong" cried Ash

"Necrozma, it's truing to drain my life plates and take away my power and add it to its own. Ash, I am fading so this may be the last time we meet as when my life plates are 100% drained, I die and turn to stone... at least I think I will be live again when you defeat necrozma..."

Arceus's voice was fading!

"Defeat the ultra beasts and don't say the word necrozma because necrozma will hear you and know where you are. It wants to kill you..."

Arceus's voice was even fainter...

Ash knew it needed help!

"Ash" the mythical Pokemon took a deep breath and said-