While passing speed would be helpful with ninjask, you never want to put all your eggs into one basket.
But let's take that since we are doing a baton pass team.
*Ninjask
Substitute
Baton pass
Leech life
Swords dance
Substitute and use swords dance to amp up leech life's power. It's a stab but also a solid heal once you get attack boosted. Make sure you have a defensive nature
*Scizor
Iron defense
False swipe( good for dealing with focus sash users, especially the level 1 variety trolls)
Bullet punch
Baton pass
I use the technician ability to increase the power of false swipe and bullet bunch. Iron defense help you make that substitute more durable.
*Smeargle
Baton pass
Ingrain
Spikes x3 this will make sweeping a lot easier against non flying types
Stealth rock
Smeargle serves as a lead trap/ingrain support Pokemon. Obviously you'll swap through baton pass a few times to make sure he has a viable substitute in front of him as well as good pass off stats. Spikes and stealth rock would all but force opponents to have to have a spinner.
After that you can use anything you want. A full chain could be hella annoying. You could opt to add another passer with double team but that's overkill TBH since Ingrain with defense buffs and substitute keep your party full. So maybe a calm mind pass if you are a mixed sweeper or amnesia if you just want that extra defense.
Lastly you could opt to split smeargle traps with another passer like gliscor which should give you pretty solid coverage against fire and rock which hurt sciscar and ninjask. That swords dance passed to an earthquake can be devastating especially with the stab bonus.
Lastly your sweeper. I prefer kabutops with battle armor . Which blocks critical hits, the only thing that can ignore stat gains. Make sure you get a fresh substitute in before you switch him in cus he's the final piece of the chain.
*Kabutops Adamant nature
Waterfall
X scissor
Stone edge (for end game)/ rock slide for doubles
Last move strictly preference. You could use double team so that Ingrain will serve it's purpose or use night slash if you wAnt more coverage