even though this meta is a mess, i'd like to throw out a set that i think is pretty great right now:
Venusaur-Mega @ Venusaurite
Ability: Overgrow
EVs: 252 HP / 252 Def / 4 SpD
Bold Nature
IVs: 0 Atk
- Giga Drain
- Protect
- Leech Seed
- Frenzy Plant
one key thing in this metagame is making sure you have more pokemon to spare, before you snowball down the everything-dies part of the match. mega venusaur, in my opinion, is a good check to almost all of the popular explosionspam sets, while still being offensive enough to where its death can pick up a KO. from full, it can survive damn near any single LW attack bar an m-glalie explosion, and with leech seed + giga drain + protect giving you a lot of health fairly safely, you can sit around that area quite a lot.
some fun calcs*:
0 SpA Venusaur-Mega Giga Drain vs. 252 HP / 0 SpD Golem-Alola: 272-324 (74.7 - 89%) -- 6.3% chance to OHKO after Stealth Rock
252+ Atk Galvanize Golem-Alola Explosion vs. 232 HP / 252+ Def Venusaur-Mega: 158-186 (44 - 51.8%) -- 14.1% chance to 2HKO
252+ Atk Metagross Explosion vs. 232 HP / 252+ Def Venusaur-Mega: 192-226 (53.4 - 62.9%) -- guaranteed 2HKO
252+ Atk Gigalith Explosion vs. 232 HP / 252+ Def Venusaur-Mega: 192-226 (53.4 - 62.9%) -- guaranteed 2HKO
252+ Atk Choice Band Slaking Giga Impact vs. 232 HP / 252+ Def Venusaur-Mega: 294-346 (81.8 - 96.3%) -- guaranteed 2HKO
252+ Atk Refrigerate Glalie-Mega Explosion vs. 232 HP / 252+ Def Thick Fat Venusaur-Mega: 318-374 (88.5 - 104.1%) -- 31.3% chance to OHKO
*keeping in mind that explosion can hit twice, though bringing a ghost type to pivot/scare off potential explosions can somewhat offset the likelihood of that happening