This should be the last achievement you get as you can easily work on the others along the way. In total you'll need to take part in 36 events. 12 in each of the 3 game types. (A win on bonus levels aren't required for any game type) This achievement took me around 3 hours in total with the Gate Relay taking the longest and Flag Rally being the shortest by far (took me 30 seconds for each match on multiple occasions)
A quick run down of the game types.
Gate Relay - Get through the checkpoints in a standard race mode, remember to do front flips to earn boost by flicking the
forward. (8 Laps minimum)
Flag Rally - Capture the flags on the map and return them to the capture point. The more flags you return at once the more points you get. 1 flag = 1 points, 2 flags = 3 points, 3 flags = 4 points, 4 flags = 10 points. (10 point minimum)
Smack Attack - Smack Attack is a game mode where your hits and kills count as your score. The pick up weapons give you points for each hit and for each kill you get an extra 10 points, basic attack hits don't give you points but will still grant 10 points if you manage to get a kill with them. (300 points minimum)