It’s not going to be a good day for Voldemort when only one of his attacks has the potential to take out Doflamingo, while every one of Doflamingo’s attacks can easily shred Voldemort’s body to pieces.
On the bright side, Voldemort does have Horcruxes hidden away, so he’s technically immortal, but that’s the only thing preventing this fight from ending in about five seconds.