To get this Offset King achievement, you must Offset 3000 times.
The most efficient way to to do this is to select [Cocoa] for arcade mode (Make sure Arcade Timelimit is on INFINITY), then as soon as arcade mode begins, interrupt it with a 2nd controller. Have the second controller choose Infinity. Choose any stage. Put Infinity (P2) in the left corner, then have Cocoa move a little close to Infinity, then spam the X button on both controllers. At the right distance you should be clashing nonstop (2 times every second).