Summary
You don't need to play 100% of the game to get the platinum. All trophies are offline. You don't have to share play with a friend to get them.
The timed score bubbles appear in front of you. They start to flick and disappear if you don't collect them all. If you're having trouble, roll to go faster. Defeat the final boss on World 3.
You and your friend must beat the score at the end of the level 20 times against the other player. Earn 50 Gold in 50 different levels. Don't die in 30 levels.
Find Gerrard on each planet in the game. Find Gerrard on the map below. See the video for each planet. Find the video here.