You saying 'Level 80s aint got no **** on us' means you are stating level 80s are unable to kill you, however there are many out there that could, you saying level 80s can basically do nothing to you is bragging as you're implying that you can take any level 80 in a fight with your five twinks as you generalize ''80s''... therefore bragging. Now you're happy to link the full imply definition however, the full brag definition states, 'say something in a boastful manner.
"he bragged that he was sure of victory" stating '80s aint got no **** on us' is saying something in a boastful manner, now boastful manners can be interpreted in different ways, If I believe you are saying something in a boastful manner then I can state whether or not I believe if you're bragging, therefore no one who has posted you're bragging has been incorrect, in fact since you've become defensive and tried correcting them all it just shows you're an aggressive character as well as attempting to brag.