Straw Hats are no longer required.
Nami? Nah. Nika can throw lightning bolts and Nika's #1 worshiper Kuma can teleport them anywhere.
Zoro? Nah. Just Nika-Smash anyone in your way.
Usoppu? Nah. Nika can make his own goggles and hit everything dead-on.
Sanji? Nah. Just Nika-Smash anyone in your way, and considering Luffy can make goggles out of his hair, only a matter of time before he pulls food out of his ass.
Chopper? Nah. Give Nika some food and he's good to go.
Robin? Nah. Nika is the past itself and can hear the Voice of All Things, so translations are no longer required.
Franky? Still needs the ship maintained I guess until Nika learns how to fly.
Brook? Nah. Nika's heartbeat already makes music.
Jinbei? Nah. Franky and others already drove the ship fine before he came. But I guess Nika needs a lifeguard until he breaks the last DF rule and learns how to control the sea cuz Nika