How are you supposed to beat the final Metalhead DLC levels?

I don’t understand how this is realistically possible. Every enemy has 10x the normal HP. I’m trying to beat Manic Metropolis and by the time I get to Shredder + Junkinator I still am doing so little damage that even if I somehow manage to dodge their attacks, I would just get bored and give up because I have a damned life to live. I cannot make any build that does anywhere enough DPS to even get Junkinator to half HP before I’m ready to just chuck my switch out a damned window.

I literally have everything in this game unlocked, I’m sitting on 130k dragon and dreamer coins and I have beaten all of the normal bosses and their gauntlet versions in 30-40 seconds with every character. Even the first levels of the DLC portals are fine but the final ones are absolutely insane and there HAS to be some secret to this because I refuse to believe the people who made the rest of the game, which I absolutely love, have designed something so absolutely garbage.

Or am I wrong? Is this just a horribly boring slog where I’m supposed to sit and focus 99% on dodging and slowly chipping away at everything so it takes me 90 minutes to finish? Is their dead-ass idea of heightened difficulty to just give all the mobs über HP and randomly put you against a room full of ninjas with AoE flame and dark moves to wreck your HP?

The closest I felt to being powerful was getting the flex where every attack was a final strike. That can get you decimating mobs pretty quickly but it still takes an INSANE amount of time for the bosses. Are the rewards better in later rooms? Should I not buy anything in the first shop and save all my coins for upgrades and dice later? Do I need to abandon the run until I get the perfect starting flex?

I’m at my wit’s end. I went from posting flex videos of me downing Shredder in 20 seconds to me wondering what the hell I’m even doing with my life because apparently I don’t know how to play this game after 250+ hours.