In random battles, every single Pokemon has a neutral nature and 84 EVs spread across all of their stats as well as 31 IVs in each stat. You can test it out for yourself. For example, Urshifu is level 80 in random battles. At that level and with 84 EVs in speed, it will reach 201 speed. You can see this below, where it says
Spe 160 to 201
If you didn't know, the number on the right will always be their speed stat in random battles. I believe the only exception to this is if Pokemon have moves like Trick Room or Gyro Ball, then they will have 0 EVs and IVs in Speed.