I think that Teach will get the Poneglyphs but not defeat Law in battle.
The scenario I can picture to see this happen is the Heart Pirates being defeated by Burgess, Auger & Q, while Teach & Law are still fighting to a standstill.
Seeing his crewmates under death risk, Law will trade the copies of the Poneglyphs to spare his men lives.
Similar to what happened with Hawkins.
This is obviously one possible scenario, Oda can do it in a lot of ways, but I'm pretty sure that Teach vs Law won't have a definitive winner and also that BlackBerry Pirates will take the copies of the Poneglyphs.