This isn't a "who would win in a fight, since as much as I love Deadpool, I think we all know he'd get his rear handed to him by Lobo. So instead, here are the rules of the battle...
Both take turns trying to figure out a way to kill each other. Literally a turn based match, like in a JRPG. Who goes first is decided on a coin toss. They are allowed to use whatever tools, weapons, call in others, whatever, from either of their universes with the exception of reality warpers (So Deadpool could try to call in Superman or Sentry and throw Lobo into a Supernova if he wants).
After their opponenet's turn, each contestant gets as long as they need to regenerate, if they are able to. Winning is through death only. No incapacitations.
Which one figures out how to kill the other first? Or do they just keep going until they both die of boredom