You need 2 copies + 2 live gold accounts. You + You or You + Friend, etc.
Create a game with more than 1 round (Just in case you blow yourself up), no pressure blocks with gametime 2:30 min.
Now, what you need to do is for the battles, just leave it be. It takes less than 48 hours pr 1000th match.
Next, you can get the bombs done here also. You need infinibomb and about 3-4x speed multiplier. Avoid picking up explosive enhancements since this will make it unsafe for you.
Now clear out the area for soft blocks so you can run in a large square spamming bombs..
You can actually keep the bombs exploding in an infinite chain reaction for about 2 minutes. It's quite fun actually.
Just DON'T kill yourself or your partner, then everything should work out.
Also, if you'd like to do the bombs/blocks adjust the game time to anything you see fit. I used the 2:30 min gametime because I was going for the 10.000 matches played.