Main Courtyard

Walkthrough: After obtaining all five Moon Shards and grabbing the ensuing Power Moon, the next set of doors will open, the same that lead to the next courtyard. Before you go through, don't forget to first look to the right to find a lower rooftop that leads to an archway. On one side of such will be Purple Coins, on the other will be another Power Moon. Use the Spark Pylon to head to the Crazy Cap Store to obtain another Power Moon. Outside of the shop, head behind it and up to the roof to find a crawlspace with more Purple Coins. From there, capture the Jizo Statue by the store and put it into place within the Zen Garden, allowing Mario to get yet another Power Moon. Proceed to the next entrance after you do.

Once you have, you will reach the foot of Bowser's Castle. However, a mysterious gate waits before you with two giant Golden Bowser Statues. Before heading up to either of them, jump onto the building to the left to grab more Purple Coins. You can also head behind the building in order to capture another Jizo Statue to find the Life-Up Heart in the sand on the other side. After grabbing those collectibles, stand on the circular arena near the left Bowser Statue to fight the Purple Broodal once more.