Ok Astro, this is going to be a bit convoluted, so bear with me.
Now, we don't have any way of knowing what EVs spread your opponent's Milotic is going to use, BUT we know what it's using right now AND we know what its counters are using.
Here is the convoluted part, so pay attention.
let's NOT concentrate on Milotic, but on the pokémons that are a good counter to it.
This link may help you.
If I was in your shoes, I would study the EVs spread of those pokémons, create a Milotic able to eliminate them AND THAN create a pokémon with EVs spread able to obliterate that Milotic.
Side ways thinking Astro.
Either way, don't be the one waiting for other people's EVs spreads, be the one making them.
Go out there and make us proud buddy!