This is how to clear crab race under 1 minute:
To start the dojo you want to do smart fireworks to the left group of blue crabs, then go the second group and use pepper spray and then dash to the top right groups of crabs and pop your snow globe and you need to kill the two groups of blue crabs and then group all the red crabs , once you grouped them together you want to take them to the remaining blue crabs in the right corner, and then pop your snow globe to kill the remaining blue crabs and after you kill the remaining blue crabs you then spam your gadgets to the red crabs until you kill all of them, good luck