Naruto Shippuuden Episode 265

[DarthEnderX]

If you reckon the sacrifice has got nothing to do with powering the zombies, then why have the sacrifices in the first place?

To make them, you know, not dead? To let them do things a corpse normally can't do regardless of their chakra. Like...move...or talk.

The very fact it does require somebody to sacrifice tells me that's where the power is drawn.

I don't think the mere existence of sacrifices is sufficient to draw that conclusion. As it still doesn't explain how the zombies have the chakra to use techniques their sacrifices shouldn't even have the chakra to cast even once.