1 Get a Gacha with BlackPearl production from Extinction

Or Farm for Them desired server such as Rag or LOst Isle

2 Travel to Crystal Island servers and find desired Tuso

3 Tame 3 to 4 low level turtles

4 Place Turtles in range of attack

5 Hit and quickly feed when Tuso attaches to your tame

PS: make sure you set a timer to know when to feed again