I can't see him losing.
Deadpool can regenerate quickly and has suffered fatat injuries
This fight would have been closer if the EU was still considered canon but now that it isn't all of Fett's feats come from the Original Trilogy and the new comic book series by Marvel. Now we didn't see much from Boba during the original trilogy, we know that he captures Han by manipulating Lando and is quite competent with a blaster. He has a reputation in the movies so I'm guessing he is a lot more dangerous than shown. Deadpool on the other hand has a healing factor which surpasses even Wolverine. He once healed back from just an arm and is quite proficient with swords and firearms. Boba's best bet would be to blast him to bits and run away from the fight but I'm going to have to give this fight to Deadpool as I think he stands a greater chance! Deadpool wins 7/10 times!
Look, deadpool doesnt die. And he has just about everything he could ever need in his pocket. And boba fett flew into the sarlac pit in the sixth movie. And 2 more times outside the movie.
I love boba fett, but in current canonical terms, he died in such an easy and stupid way. Deadpool can regenerate! He can't lose!
deadpool chops boba,s head off.