right now im taking one low lvl pet i want with me to the forsaken dungeon boss battle, i purposely die at the boss and get huge exp and revive all pets and retry the boss battle, and while it does give good exp its a bit tedious and my battle record per pet looks very bad since im losing on purpose.

are there other ways to quickly lvl up a low lvl pet to catch up? my 3 highest are lvl 50

Well I can think of two ways.

The first is missions since pets get exp from missions and you get stuff from completed ones.

But if you wanna do something similar:

Pets if they are too high don't get xp or very little of it, So if you go to another area that is low enough that the pet won't die but high enough that you get a bit of a fight with them you can actually net a fairly good amount of xp.

Just remember to not put your low pet in slot one because that's the one that takes the most damage.

The easiest way is to use experience orbs. You can find them on the trade broker. Go for orbs level 40+

uhh nice one, lvl 50 are quite cheap too ^^