There is 5 categories that you must gold.
Attack
Defense
Drift
Jump
Beat (made with the right analog stick) "invested"
For Defense, Drift, Jump, "invested":
Start a local race with 2 players. You and 2nd controller. Choose the level with the soccer stadium.
Drive both controllers to the soccer stadium.
Drift: Drift around in a circle for about 15 mins or so. I think you need around 500+points? I don't remember. You can keep going until you feel like you have enough to get gold. Also a good way to do 500 3rd level drift turbo
Jump: Jump on your 2nd controller, make a small circle and jump your 2nd controller again. Keep going for about 10-20 mins depending on how often you get the jump points.
"invested": Similar to jump but does not connect as much. Drive up, "invested" to the side, turn around, drive again ,ram again. You need enough speed so you can ram. About 20-25 mins maybe.
Defense: When your main profile is in 7th place, when you draw items from the box, occasionally you can get 3 bowling balls. Shoot them at the soccer players and it will count as defense. If not, you can shoot the parade cars before the finish line and those will be defense. Time it takes here depends on how lucky you get with item draw.
For attack:
Start a local race with 4 players. You and 3 controllers. Choose the level with the soccer stadium
Attack: When you are 6th place, very often you get the homing airplane. Shoot it at a controller that is in 5th place. Repeat until you have many points.
Credits to : "MemoriesOfFinal"
how it helped me in this achievement I decided to post to help those in need too! good luck!