Pure

This can be done with you and a friend host a player match turn AI off all you have to do is 1trick and then let it run out of gas repeat again for your friends

Best method is like what is stated above, simply aim for doing every unique trick using each button. However, if you are like me your favorite tricks are habitually going to be Up on the right stick with a button. If so just know that from my experience pulling 3 tricks between each use of a trick will allow the trick to be fresh again. So if using A tricks just mod it then do another trick and mod it.. this will make the original A trick fresh again.

You can get a two-in-one achievement here easily(if you haven't done the other one already.) Go on to Phu Temples Freestyle either stage 9 or 10, then from the off hold the multiplier from the first ramp to the first ramp going into the rock crevices bit...seems hard but it really isn't, just keep hitting boost and obviously using fresh tricks, by the time you get there with that multiplier, should be about a x9 with a special trick probably, there are some huge jumps, then you will also unlock "Killer combo" too, this was the best method for me anyway.