I was playing an RU match and utilized a SubPassing strategy. The opponent laid Toxic Spikes, I baton passed to my set-up Sweeper with the Sub intact, but my recipient was poisoned anyways. Sub should have blocked the poison from Toxic Spikes (at least that's how it has always been in BW1 on PO).
That's how it used to work in Gen 4; in Gen 5 Baton Passing a Substitute will not prevent poison from Toxic Spikes (but switching in with Safeguard up still does).