I'd suggest running either toxic or grass knot on your zera, with proper prediction you're able to massively threaten teams that rely on those defensive cores. This would however require removing either Close Combat or Plasma Fists preferably, so adjust that to whichever you want to threaten.
Yeah grass knot definitely has merit on it
-CALCS-
0 SpA Zeraora Grass Knot (120 BP) vs. 252 HP / 0 SpD Hippowdon: 230-272 (54.7 - 64.7%) -- guaranteed 2HKO
0 SpA Zeraora Grass Knot (80 BP) vs. 252 HP / 252+ SpD Swampert: 180-216 (44.5 - 53.4%) -- 0.4% chance to 2HKO after Leftovers recovery
0 SpA Zeraora Grass Knot (60 BP) vs. 252 HP / 4 SpD Gastrodon: 208-248 (48.8 - 58.2%) -- 95.7% chance to 2HKO
(if anybody still uses it)
-OTHER MOVES-
252 Atk Zeraora Knock Off (97.5 BP) vs. 0 HP / 0 Def Nidoking: 119-140 (39.2 - 46.2%) -- guaranteed 3HKO
252 Atk Zeraora Close Combat vs. 0 HP / 4 Def Garchomp: 123-145 (34.4 - 40.6%) -- guaranteed 3HKO
252 Atk Zeraora Close Combat vs. 96 HP / 0 Def Regieleki: 204-241 (62.7 - 74.1%) -- guaranteed 2HKO
252 Atk Zeraora Close Combat vs. 0 HP / 4 Def Rillaboom: 129-152 (37.8 - 44.5%) -- guaranteed 3HKO after Grassy Terrain recovery
252 Atk Zeraora Close Combat vs. 0 HP / 4 Def Excadrill: 354-418 (98 - 115.7%) -- 87.5% chance to OHKO
252 Atk Zeraora Plasma Fists vs. 252 HP / 192+ Def Tapu Fini: 204-240 (59.3 - 69.7%) -- guaranteed 2HKO after Leftovers recovery
252 Atk Zeraora Plasma Fists vs. 252 HP / 252+ Def Slowbro: 200-236 (50.7 - 59.8%) -- guaranteed 2HKO
252 Atk Zeraora Plasma Fists vs. 252 HP / 252+ Def Toxapex: 158-188 (51.9 - 61.8%) -- guaranteed 2HKO
252 Atk Zeraora Close Combat vs. 252 HP / 252+ Def Blissey: 428-504 (59.9 - 70.5%) -- guaranteed 2HKO
252 Atk Zeraora Close Combat vs. 252 HP / 0 Def Heatran: 226-266 (58.5 - 68.9%) -- guaranteed 2HKO after Leftovers recovery
252 Atk Zeraora Knock Off (97.5 BP) vs. 0 HP / 0 Def Latias: 208-246 (69.1 - 81.7%) -- guaranteed 2HKO
There are a lot more, and it's damage output isn't crazy or anything, however it is a extremely good late game cleaner, and decimates a lot of stall teams. Not many of the ground types like switching in on CC or a Knock Off. It can even be a soft check to Torn-T.