A few optimizations I noticed could be made a few months ago:
the berry lando spread accomplishes the same goals with 248 HP;
+1 252 SpA Genesect Ice Beam vs. 224 HP / 0 SpD Yache Berry Landorus-Therian: 334-394 (89 - 105%) -- 31.3% chance to OHKO
252+ SpA Deoxys-Attack Ice Beam vs. 224 HP / 0 SpD Yache Berry Landorus-Therian: 332-392 (88.5 - 104.5%) -- 31.3% chance to OHKO
you labeled these as guaranteed survivals. I know 252 SpA Gene isn't standard, but +SpA Deoxys is a legit set imo.
92 SpA Diancie Moonblast vs. +1 0 HP / 4 SpD Kommo-o: 288-340 (98.9 - 116.8%) -- 93.8% chance to OHKO
labeled as guaranteed KO;
The Gastrodon set can get 4 extra EVs by changing the HP to 248. Also, if you dont care about the special bulk, Quiet can give you 3 total stat points extra with 248 HP/228 Def, sacrificing 10 SpDef for 13 more SpA. Another option is going Sassy and 32 SpA, which makes the roll on Inci a mere 99.2% chance of KO'ing, but gives you the same stats everywhere else with 2 extra points in SpDef;
252+ Atk Landorus-Therian Superpower vs. 252 HP / 16 Def Incineroar: 334-394 (84.7 - 100%) -- 6.3% chance to OHKO
This calc could be an issue on the Inci spreads;
252 Atk Tough Claws Metagross-Mega Iron Head vs. 252 HP / 32+ Def Tapu Fini: 144-171 (41.8 - 49.7%) -- guaranteed 3HKO
As you can see, you don't need as much defense on the Fini for the benchmarks you mentioned and, since SpA is just a dump, you can go Calm 252 HP/140 Def and give Fini a net gain of 10 extra points.
The banded Zygarde spread can accomplish the same defensive goal with 24 HP/ 56 SpDef, while also allowing you to max out on its Attack.
The berry Zapdos set can accomplish the same goals with 244 HP/56 Def/56 SpDef, but gives you 8 extra EVs.
These are the only ones I can spot right now, I hope it was helpful.
the berry lando spread accomplishes the same goals with 248 HP;
+1 252 SpA Genesect Ice Beam vs. 224 HP / 0 SpD Yache Berry Landorus-Therian: 334-394 (89 - 105%) -- 31.3% chance to OHKO
252+ SpA Deoxys-Attack Ice Beam vs. 224 HP / 0 SpD Yache Berry Landorus-Therian: 332-392 (88.5 - 104.5%) -- 31.3% chance to OHKO
you labeled these as guaranteed survivals. I know 252 SpA Gene isn't standard, but +SpA Deoxys is a legit set imo.
92 SpA Diancie Moonblast vs. +1 0 HP / 4 SpD Kommo-o: 288-340 (98.9 - 116.8%) -- 93.8% chance to OHKO
labeled as guaranteed KO;
The Gastrodon set can get 4 extra EVs by changing the HP to 248. Also, if you dont care about the special bulk, Quiet can give you 3 total stat points extra with 248 HP/228 Def, sacrificing 10 SpDef for 13 more SpA. Another option is going Sassy and 32 SpA, which makes the roll on Inci a mere 99.2% chance of KO'ing, but gives you the same stats everywhere else with 2 extra points in SpDef;
252+ Atk Landorus-Therian Superpower vs. 252 HP / 16 Def Incineroar: 334-394 (84.7 - 100%) -- 6.3% chance to OHKO
This calc could be an issue on the Inci spreads;
252 Atk Tough Claws Metagross-Mega Iron Head vs. 252 HP / 32+ Def Tapu Fini: 144-171 (41.8 - 49.7%) -- guaranteed 3HKO
As you can see, you don't need as much defense on the Fini for the benchmarks you mentioned and, since SpA is just a dump, you can go Calm 252 HP/140 Def and give Fini a net gain of 10 extra points.
The banded Zygarde spread can accomplish the same defensive goal with 24 HP/ 56 SpDef, while also allowing you to max out on its Attack.
The berry Zapdos set can accomplish the same goals with 244 HP/56 Def/56 SpDef, but gives you 8 extra EVs.
These are the only ones I can spot right now, I hope it was helpful.