What's the EV hit actually do in LV50 All?

[Siigari]

Like the title says, does LV50 All just reference your Pokemon's IVs at level 50?

 

[Abyssion]

Your pokemon will keep their EV's, IV's, base stats, evolution, and move sets, but the pokemon's level changes. It'll be what they would be if they were at lv 50 instead of whatever their level is.

 

[MegaDitto]

If you have a EV trained pokemon at level 50. Only half of the 64 points will be there.