You can try using only unlimited box space, set damage multiplier at 1 and turn off god mode. You can do this or stop playing or play the game with a clean version.
What are those 6000+ units? Don't sell them. You can use the dupes to Level limit break all of your legends/RR/LRR/Kizuna RR/TM RR and the farmable characters from arena/recollection archive/TM & Kizuna f2p units. Keep 1 copy of legends that will change their colour/class/special effect/rumble ability or special and so on. A great example is TS Luffy: his 6

version is QCK but his 6+

becomes PSY and his effects change. His 6

his needed to complete grand voyage lv.5 against Buggy and people need him as FC with max LB and max LLB plus a lot of ATK CC. This is an improvement very important for non-modded players but is also good for modders that will think about dropping the mods.
You have cotton candy in the box? Sell all because it will be stored in an "hidden box" that doesn't take space. Sell all of your 1

/2

units that don't evolve and all the useless farmable characters like navy/pirates fodders like the ones the the screenshot.
Sell all evolvers that don't stack, use the boosters that don't stack to increase the level of your level-limit-breaked units so you make lots of space, keep all of your evolvers/boosters that stack.
For any doubt or more info send me a PM.