Booster Hill is a minigame where Mario can earn flower points. The max is 15 or 16 flowers.
Jump on the barrels and snifit heads to touch Peach/Booster to get one flower.
The isometric view during this game makes it tough, as hitboxes seem to be non-existent sometimes.
14 Flowers is ideal to be set for the rest of the run if going for Smithy Chest Head Gamble; 11 otherwise (You need 24 FP total by Yaridovich. 26 is required by Countdown, but more FP may be useful in case of bad luck (36 is ideal for a worst case scenario on Countdown)).
If you end up being short on flowers, there are other points in the run you can collect them.
If you do REALLY poorly on Booster Hill (less than 8 flowers) to the point where backups between here and Yaridovich won't get you to 24, you have 2 options:
Use tabs/jars/boxes in your inventory to make up the difference, and buy less bombs in Seaside Town (much faster, requires you to know what you're doing)
Re-enter Booster Hill and pick up 2 flowers lying on the ground after the barrel segments, repeat until you have collected 8 in total (VERY slow, only recommended if you absolutely cannot reset and aren't comfortable adjusting your bomb counts)
Tip: In the barrel phase, stay up at the front at all times. Barrel frequency is constant, but where the barrels spawn is random.
Tip: In the snifit only phase, if you hit Booster, he will run far ahead to where you can't reach him. If you jump on a snifit right away, it's possible to miss Booster as he falls back to the pack. You can get another hit on Booster without missing a cycle if you wait slightly and try to hit a snifit as Booster is moving backwards.
Tutorial by Justin: https://www.twitch.tv/videos/201020547