Best track record of sparring mates becoming champions

Fighters spar with everyone Tommy hearns sparred with Ali

Who knows??boxers have sparred with pretty much most of the other boxers sometime in their boxing careers. While it is true that boxers spar each other often.... I don't see how you could say "most." I don't think paq's habit of regularly sparring fighters that become world champions is typical. It seems to me that Chavez and Ali are the only ones that have regular sparring mates that became champions.

Chavez Sr. sparred with Mosley, i think it was for one of the Taylor fights. Tyson sparred Oliver McCall (lol) Ali sparred Holmes for Foreman.

Who knows??boxers have sparred with pretty much most of the other boxers sometime in their boxing careers.

Every fighter spars with someone better than them as that is how you learn. So, everyone was someone's sparring mate at one point. Although there is a difference between a journeyman/average boxer being used for sparring like Beltran and a prospect like Porter and Khan sparring with Pacquiao. The former "normally" doesn't have any hope to do well and is a designated punching bag of sort, while the latter is using the experience to go up in levels. So, the only name that stands out is Beltran because no one expected him to do well. What I'm really curious about is if there are other boxers that have sparred with this many champions? Usually, you hear random sparring sessions like Peterson mayweather or Chavez vs. de la Hoya. But pacquiao spars these guys for years. Then they end up being champions. Wondering if there are others.

Oliver McCall.

Jimmy Ellis.

Two up and coming fighters that Pacquiao sparred that have potential of getting a world title are Zou Shiming and Lydell Rhodes

Duran sparred Chavez? I wanna see that. I seen footage of Duran sparring Nigel Benn I think I'm mistaken actually...

Every fighter spars with someone better than them as that is how you learn. So, everyone was someone's sparring mate at one point. Although there is a difference between a journeyman/average boxer being used for sparring like Beltran and a prospect like Porter and Khan sparring with Pacquiao. The former "normally" doesn't have any hope to do well and is a designated punching bag of sort, while the latter is using the experience to go up in levels. So, the only name that stands out is Beltran because no one expected him to do well.

Duran sparred Chavez? I wanna see that. I seen footage of Duran sparring Nigel Benn