Top Spin 3

if you have 2 boxes and 2 copies of the game:

quitting out works. but only for the one who's not quitting (the winner).

i just quit out of 50 matches on each side (with lvl 30 characters to match up easily + playing out the first point) and bamm, after 100 matches of quitting my main account got both achievements: 100 mixed + world career.

if you don't get it after said matches try and complete a full match either on womens or mens tour and you should be good.

thanks ginnorz for pointing out that BOTH accounts get the achievement. so if you're boosting this with a buddy this will be done even faster now.

World Tour = ranked matches, you need to play 50 matches as a female player and 50 matches as a male player. The matches have to be completed, quiting out will give you a loss, but the match won't count towards your played matches

My solution is for 2 xboxes and 2 turbo pads :

You create 2 new players male (1 on each console) and 2 females( same ).

Now you go to world tour and you choose your 2 brand new players.

Go to quick match and search with first account. When you are on the search game menu, do quick match on the second xbox.

You will find each other as there is no one left on the servers.

You can ready up and program your 2 pads.

On the second account you program A and RT on turbo mode at full speed.

On the first account you just program A button at slowest speed.

Now you can sit and look sometimes to see if the matchmaking has worked. Sometimes when you go to the menu the 2 xbox launch quick match at the same time and they can't match. Simply push the B button on the second account and it will quit and reopen automatically since you have the A button on turbo.

When you have won 50 games you can switch to woman and do the same thing.

Please if you vote negative explain why in a comment, so i can improve the solution.