Well u may not know that attack speed nautilus is rly rly rlyyyyyyyyy strong becouse hes w.. He just can do so much dmg on multi targets in teamfights.Well a lot of peoples build him pure tank i think that he dont shine in that position becouse hes made for solid dmg great hurras off tank bruiser...
U maybie now watch that start with items and say this guy is creazyyyyyyyyyy hes noob he dont know how to play and dat stuff but i tell u this way of playing nautilus is gr8 :)
If u dont trust me try it yourself i tell u that it will be 99% wictory :))

Nautilus is GR8 GANKED! He rly shines in early in mid game becouse TONS OF CC. U can do lvl 2 gank with only your Q pull you to themselves and stun them with your passive. its almoust 100% kill or burn of summoners.If u dont do lvl 2 gank u must go gank at lvl 4.
This is your lvl 4 combo:

Open up with q or if u can walk up to the target do it and stun him wit your passive,
then press your w for dmg, e for slow and try to burst him.. if u walked up to him and do this even when he flash u can secure the kill with your q.

gank at lvl 6 :

open up with ult, come close to them,stun them,do dmg with w,slow them and secure kill with exhaust and q..

IT is :
wolves
golems
wrates
lizards or if u like double golems then lizards ;)
Aggresive route:
boots+ 3 pots(u start with) go do blue golem with help of teammates(smiteless)
leave little guys alone( i will ex. why)
go to they red pull it in bush and steal it :)
if enemy dont see u go gank top if he see u go protect your red!! and do normal jungle route(u need to leave little guys alone becouse then u will know both timers his and your blue and u can go steal his and then come to give your mid blue ;)
Gank route:
go wolves-golems and gank top or bot then go steal his wrates and see if u can more couterjungler becouse nautilus is very fast.Be sure that someone ward your red that they dont steal it.

Ok here u go:
Nautilus is initiator. Open up with q and try to do passive on everyone dat u can have lead.Do w ofc for high burst dmg that is aoe.
Ult carry dat ult can follow him and he will need to run or to stay alone that hes team dont get knocked up.Anyway hes scruved.If u do this teamfight is yours.

(SRY IF BAD ENGLISH I AM FROM SERBIA SO...)