People who are not "educated" about dogs seem to think that bigger is better. Fighting dogs such as pit bulls, boxers, amstaff terriers are medium size for a reason.
Especially tall dogs such as great dane are not made for fighting other dogs, and would get killed by a boxer or pitbull. While the american bulldog is also rather tall, it packs so much muscle that it devestates other dogs with its brute strength. Unfortunately after 15 minutes they have enough and don't want to fight anymore.
The most dangerous dog in the world is a 75 pound pitbull period. Boxers up there too, but pitbulls have been bred for gamness in the last 50 years while the boxer has not. There is speculation that the japanese tosa rivals the pitbulls fighting prowess but they are not nearly as game, or as quick.
The AKC and CKC breed standard for boxers is 22.5 - 25 inches at the withers and 75lbs. I know that with boxers its easy to pack a ton of muscle on them but I have never before today heard of a boxer who weighs over 130 pounds. I'd really like to know where you got him, and if they have a website.