Borderlands – Can’t level up after level-50 in borderlands 2 in True vault hunter mode

Yes; boss levels are treated like normal enemies levels in THVM, so as long as a boss is no longer part of a mission (meaning you've completed and handed in the mission) and you're in playthrough 2.5, the boss will scale with your level. Their loot, as always, is tied to their level, not yours, and capped at the level cap.

But effectively that means at level 50 in playthrough 2.5, repsawning bosses will be level 50(ish) and drop level 50(ish) guns. At all other times (during missions, before beating Warrior a second time) boss levels are locked in due to their mission/area levels, just like playthrough 1.

wow, old question, so my answer is probably late.

I play a mechromancer. I've not gotten to UHVM yet, but I've solo'd most of TVHM so far with very little problem (I do die occasionally, but I never got 'stuck')

I invest in anarchy (I keep the stack limit at 150) with maxed type I iconocast and rational anarchist. I always pack a one-shot jakobs; even if its weak; purely to build anarchy; though you have to be far from the enemy and stay safe while you charge it up. It takes very little time to get to 100 stacks and Deathtrap does a fine job at keeping them from getting to me while I charge up. At about 100 stacks or so, I switch to my main guns and start chewing through enemies very quickly. Anarchy, at least for me, has been key for Mechromancer. Shotguns are your friend; 5/5 close enough, standing close to the enemy, and 150 stacks of anarchy = awesome offensive power. Throw in 5/5 bloadsoaked shields and you can stay alive as long as you keep killing stuff; an easy thing to do with the anarchy/weapons mentioned above.

Rest of my points generally go into Best Friends Forever tree to beef up Deathtrap. He is seriously a beast even on TVHM late game; so long as you spec him for it.

I do admit; I am nervous to see how this build fares in UVHM..