Question

What's the best way to get a 6IV Ditto in Pokemon X/Y?

Answer 1

Luck or trading.

That's the only way to get a 6IV Ditto without cheating since you can't breed them.
If you have a friend safari with a Ditto, you are guaranteed 2 perfect IVs, other than that you have to be lucky.

You could chain them to increase your chances as well, but that would take a bit of skill in chaining too.
[Here][1] is a guide on chaining.

And as fondant commented, this has a high chance of breaking before getting to 61, so I wouldn't rely on it.
[1]: https://www.smogon.com/ingame/guides/chaining

Comments

Yes and to proove it I lend you my best and most powerfull pokemon a modest mewtwo with Attack Sp.Attack and Speed IVs so you know I'll want it back.

---

Togekiss,Electivire,Gallade,Mega Kang,Volcornia,Kingdra

---

That Mewtwo Is my most favret pokemon I have so I'll want it back.

---

Nvm lets do the cloneing part

---

Ok but I can't do it for a few hours if thats ok?