Mew's best moveset

Take this how you'd like, but there's about 10 of these topics on the first page. Perhaps take a look at them?

What are you planning to use it for? I don't find double ice very useful since he is not better at this role than other ice Mons, and there are many of those.
I will try to get Volt switch/Rock slide, I think this combination will be quite useful if the birds come back.

Unless you are someone with hundreds of TMs lying around, it seems like a fool's errand to try to create a specific mew moveset.

I would have recommended a double rock moveset (since golem is still the only relevant pokemon with one at this point), but mew doesn't have a fast rock option.

That's a good relevenat moveset right now. Frost Breath will charge Ice Beam quickly and you can go use it as a bulky counter against Latios and show it off