We find ourselves not with Ash but Clair then Whitney and Jasmine appear

Jamine:Still thinking how his gonna treat you
Clair:Yes I mean I took one of his eye and hurt him I think that machine is rig
Whitney:It wasn't but don't worry I think everything will be fine probably
Clair:Not helping sow did they buri kukui
Jasmine:Yes and his elites and Kahuna's are still there
Clair:Well he was there friend
Whitney:There was also a stranger there
Clair:Did they say his name
Whitney:Guzma and I did some research and it looks like he fought Ash in the alola league
Clair:Wait really and who won
Whitney:Ash
Clair:Actually that makes sense
Jasmine:Well I which you good luck
Whitney:Yeah good luck girl
Clair:Okay

The next day Clair is walking to the Pokémon Center

Clair mind:Okay you got this it's just training and maybe he will forgive me in are training

(Hell no he won't)

Has she comes to the center she sees Ash waving two girls and his meloetta then he noticed her and went to get her

Ash:your late
Clair:Wait no I'm not we're you expecting me to come early in the morning
Ash:Yes but now you are here sow come on

Has she followed Ash into the forest we're they reach and open area

Clair:Sow this is we're you have been training
Ash:Yes and let's start bring out your strongest Pokémon
Clair:Why
Ash:Because if we mix your Dragons with one of mine are team work might be good enough to move on seen when we beat Anabel and Misty then I kill her are next opponent are Marshall and Chuck
Clair:Oh okay Dragonite come out

Ash:Okay come out everyone

Garchump,Sceptile, Goodra and Guzzlord appear
but when Clair saw sceptile she got confused

Clair:Ash why is Sceptile there he is not Dragon type
Ash:Well in his current state not but when he mega evolve yes
Clair:Okay sow why you bring them out
Ash:If we are gonna find a partner for your Dragonite she must choice who her partner is gonna be
Clair:Oh now I get it that way we can work together perfectly
Ash:Hold your horses I'm only gonna trust you for 3 days sow don't waist time.Sow now send Dragonite to pick a partner
Clair:Alright Dragonite go pick your partner

Has the dragon comes toward the four other dragons
she looks had them but then she looks had Goodra and she decided Goodra

Ash:Guess are lucky winner is Goodra
Clair:Okay sow now what
Ash:Now we train Articuno,Sylveon come out
Clair:Cool that's the second legendary you have showed
Ash:Okay sow before we start training had the same time you must first conquer Dragon type weakness which is ice and fairy and are fight is later sow we got time
Clair:Alright lets start

Hours pass and there fight was getting close after that they were taking a break sow they can do one more fight and go to the stadium

Ash:Okay you doing good but ice still your biggest weakness
Clair:I know sow Ash why did you decided to kill the leaders of the evil organization
Ash:Simple I'm not dumb like you guys
Clair:Hey how dare you we tried are best but they just got away and even if we did catch them we would not kill them because that is not the way
Ash:Idiot if you let them live there just gonna come back and kill more people and steal Pokémon
Clair:Will you maybe right there still humans
Ash:Humans that have lost there way
Clair:Dang it I cant fight you sow and what happened before that
Ash:You really want to know me
Clair:Just answer the question
Ash:I went to kill all my old companions,Rivals and the families of those gym leader assholes
Clair:Sow it was you who killed them but why then why not just your companions and Rivals why you killed innocent people
Ash:Because I wanted to make them suffer the same pain and may I say I haded some revenge after what you did to me
Clair:Look I'm sorry for taking your left eye away waif you said revenge for what I did what you mean
Ash:Clair do you remember Dragon Village
Clair:Yes that's we're me and lance grown up wait the death,the snow and the Pokémon

Flash back

In Johto with Clair and Lance going to there home town Dragon Village

Clair:Is been some time seen we left home wonder if anything has changed
Lance:Well if better have seen they did not let me help them when I was starting to be Champion here

Has they arrive they see the death the Pokémon and the village killed and destroyed

Clair:what happened here

Flash back end

Ash:Sow what you gonna do about it
Clair:Dragon pulse
Ash:Huh

The attack made a smock screen which then she took advantage and ran away but it was to late because Mewtwo hold her and Dragonite with psychic

Clair:let go of me you monster
Ash:Sorry Clair but you should have not done that sow prepare to die
Clair:Wait no Ash aaaahhhhh

Has she dead then Ash using one of her pokeballs returned Dragonite

Ash:Okay let's go finish this Mewtwo you and scizor will be the Pokémon I'm using
Mewtwo:Okay Ash what about the body
Ash:Leave it

Has they went to the battlefield we're ash arrive early and told ref that his fighting alone and he was okay with it then misty and anabel came

Anabel:Ash were's Clair
Ash:She did not want to come sow I'm fighting alone
Misty:Hah you think you can beat us by yourself your more dumb than I think
Ash:Is that sow
Misty:Yeah Anabel step back I'm doing this on my on one vs two
Anabel:Fine
Ash:Perfect now I can destroy you
Misty:let's see about that Gyarados come out
Ash:Well time to break her Mewtwo and Scizor

The three Pokémon appear and line always misty freaks about the bug type

Misty:Gyarados mega evolve and kill that thing

Scizor:What she say to me
Ash:How about we teach her a lesson Mewtwo Scizor mega evolve

Mega Mewtwo:This was over before it even started
Mega Scizor:yeah let me go first sow I can destroy that monster
Ash:Okay use Flash Cannon
Misty:Gyarados don't let that thing touch me Hyper Beam

Has the attacks collide explosion happens

Ash:Use scrunch and throw that thing to the wall then Flash cannon

Has the gramps or bites Gyarados with his giant claw his throw him to the wall with he than shoots him with a Flash Cannon

Ref:Gyarados is unable to battle
Misty:How did I lose to him
Anabel:Looks like is up to me espeon let's go
Ash:Really espeon you are potting all your hops on Espeon against my mega evolve Mewtwo who is a psychic and fighting
Anabel:I won't lose and will bring you back to the light and I know your lying about Clair
Ash:Is that sow then let's end this Mewtwo mega punch
Anabel:psych.!
Ash:too little to late

Has she could not finish what she said because Mewtwo already punched espeon and send her to the wall like Gyarados

Ref:Espeon is unable to battle the winner is Ash
Anabel:it ended sow fast
Ash:You should have use your Metagross

Has the 3 leave thru the tunnel anabel behind

Ash:Well time to end this
Misty:End what
Ash:Your life Mewtwo teleport
Mewtwo:Finally
Anabel:Wait no Ash stop

It was to late she was teleported to her death but Anabel saw everything

Anabel:Ash why
Ash:Because she deserves it and you saw everything sow I can't let you live
Anabel:Wait Ash stop don't come any closer
Ash:Good bye Anabel

Has he breaks her neck and leaves her there

Ash:Well lets end this tournament

After that ash keep winning and he reached the Finals we're he defeated Diantha with Meloetta after words came Miette tournament which she also won and had the end Ash lives with his angels not regretting what he did

End

(Sorry it was short but this story was not about Ash being becoming the strongest it was Ash becoming and Assassin or killer)