For this, you'll need a computer and UDP Unicorn (A Program)
I could've made a ton of money using this service since barley 10 people knows how to do this and i'm not going to be a scum.
1. Go on the HIGH level account.
2. Go into Headquarters.
3. Hover over "Switch Profile"
4. Turn on UDP Unicorn
5. Press on the account you want your stats duped on.
6. Wait until you see a black screen and the Controller Pairing screen appears.
7. Turn OFF UDP Unicorn
8. Spam B until it says "READING DATA"
9. Spam A to go online
10. Wallah, You're prestiged/duped stats
11. Go into a game of TDM or whatever to make the stats stick.