How many GDDL tiers does beating something on mobile 60hz buff the level?

I just beat B as a new hardest on mobile 60hz. Right now, one of my friends has Verity as his hardest, which he beat on a good PC. I bet him that I could beat a harder hardest than him within the year. Seeing as each level is only separated by one GDDL tier, I think that there's a chance that mine could be harder. We both agreed to let reddit decide.