I would like to know which one of Sheiks killing moves Sheik mains use, to well actually kill? Do you just transition to Zelda?
#1 Nair when over the pit.
#2 DSmash at the ledge
#3 USmash, wether it is normal, hyphen or DACUS
(best KO move IMO)
#4 Vanish
Just as a tip:
I main Sheik only. I use Zelda just as a boost of strength. However, it is not smart to Transform in the middle of a fight. There should only be about 3 situations that you should transform.
#1 When you knock the foe FAR away from you.
I usally don't use this one. Reason being is if they are already far away then next time they are in Sheiks KO percentage.
#2 When you (you have to have a lot of damage for this to apply) and the foe are at high percents and you are almost out of the screen. This way you can have a safe transformation.
You can also charge needles in this same situation.
#3 When you are KO'd and your opponent is at high percents you can do a jump and then Transform. By the time you reach the ground you will be Zelda and you will have just a split second of invincibility frames. Be ready to shield.
Get your KO in and turn back into Sheik.