Mega Lopunny A+ --> A
With the meta shifting away from Hyper Offense towards slower bulkier teams, Mega Lopunny has taken a hit. Compared to things like Mega Medicham, which has been rising in popularity, M-Lop lacks the power it needs to break through common defensive cores, unless it uses Power-Up Punch, but that means giving up Ice Punch, which leaves it helpless against stuff like Lando-T and Garchomp.
+1 252 Atk Mega Lopunny High Jump Kick vs. 244 HP / 216+ Def Tangrowth: 208-246 (51.7 - 61.1%) -- 94.9% chance to 2HKO after Leftovers recovery
252+ Atk Pure Power Mega Medicham High Jump Kick vs. 244 HP / 216+ Def Tangrowth: 246-289 (61.1 - 71.8%) -- guaranteed 2HKO after Leftovers recovery
+1 252 Atk Mega Lopunny Return vs. 252 HP / 232+ Def Slowbro: 178-210 (45.1 - 53.2%) -- 0.4% chance to 2HKO after Leftovers recovery
252+ Atk Pure Power Mega Medicham Thunder Punch vs. 252 HP / 232+ Def Slowbro: 204-242 (51.7 - 61.4%) -- 96.9% chance to 2HKO after Leftovers recovery
Even at +1, it does less damage than M-Medicham. Now, the gap is closed a bit if Mega Lopunny is Adamant, but unlike Mega Medicham, it can't really afford to go Adamant, as its speed tier is too crucial, and Mega Medicham still has more immediate power.
Now, Mega Lopunny is still a good mon, but recent trends in the meta haven't been kind to it, and it has no business being ranked above Mega Medicham, and it clearly isn't as good as some of the other Pokemon in A+ right now.
I also agree with moving Mega Medicham up to A+, for the reasons that already been stated.