What if Leonardo was alive in 2019? How would he look?
Leonardo takes being a ninja extremely serious. And he is too stealthy, patient, and deadly to be a Red Earred Slider turtle. But there are turtles the same size as them, who ARE deadly, patient, stealthy, and like assassins naturally. Those are the Mata Mata turtles.
This imagines Leo as a matamata, who can sit in sewage, or a pond, or a dumpster, for hours or days, without moving, until he strikes his target. Since Leo is a serious ninja, he would never just have two katanas, he has one that is sentimental, but as a ninja, he would try to scavenge the best weapons for the job.
This Leo wears custom shoes made from thrown-out scuba gear, gym shoes, and cotton so his claws dont clack against the ground. He has a customized sniper rifle, a wakazashi made from reforged metals, a giant razor blade, and anything else he can find that a ninja would value.