Welcome to the mewverse in this reality or world Ash keep doing his adventures but what if Ash fond Mewtwo in the forest injured then he took him in and took care him and Mew and after a Moth they Fond the Mewtwo Ash's meet in Unova and after that they all got along they mostly stayed with Ash because he has a habit of almost dying when there
Legendary Pokémon around sow he keeps a close eye on him but this time he is in Kalos now Mewtwo in the roof looking had the sky(Also female Mewtwo will be called Newtwo because that's people call her)

Mewtwo:Hmmm

Flash backs

Mewtwo his on the couch with Newtwo watching tv has they see Kalos news and see that Ash trying to stop Garchop and then see him jump of the building to pikachu

Mewtwo:That idiot Mew do something
Newtwo:Wait look

Has they see mega blaziken save him

Mewtwo:Arceus thank you
Newtwo:When did you get like that
Mewtwo:I have no idea what your talking about

Has then they see the tournament and Ash's first match and he shows Ashgreninja

Mewtwo:What is that
Newtwo:Looks like mega evolutions but with now key stone or mega stone and only legendary Pokémon can mega evolve without those
Mewtwo:Let's see if he will explain when he gets back

Then they see the Kalos Crisis were they see ash in the fight with pikachu and Greninja and as you could tell same worried expression came out of Mewtwo

Flash backs end

He keeps looking had the sky until new teleports in front of him

Mewtwo:What do you want
Mew:Mew Mew Mew
Mewtwo:I know I'm being to protective but you know as well as I do that he gets into to much trouble and had least those 3 idiots stop chasing him

Then Newtwo comes

Newtwo:We know you miss him so do we but can you really stop that personality of his
Mewtwo:Point being
Newtwo:We both know Ash is a person who would sacrifice himself  for others especially Pokémon he even tried to stop you and Mew from fighting and thanks Arceus he came back to live so just be glad he comes back tomorrow
Mewtwo:Fine you made your point that personality is what makes Ash well Ash and I think nobody would change it not even me he save me from a falling tree even knowing I could just use psychic
Newtwo:You never told me about this
Mewtwo:You know we don't need to tell you everything
Mew:Mew mew
Mewtwo:What do you mean I'm being to cold
Mew:Meewww
Mewtwo:Fine I'm sorry
Newtwo:I'll forgive now let's go to sleep
Mewtwo:Wait is that him

Has they see in a distance Ash running and Pikachu on his shoulder they thought it would be better if they meet him inside and few seconds later Ash comes in and opens the door

Ash:Guys I'm home
Delia:Sweetie you back
Mewtwo/Newtwo:Ash!

Has he gets psychic pulled into a hug by the Mewtwo's