Oathkeeper
"Wait!" he says, do I look like a waiter?
Well, let's see here:
This thing is an absolute monster! Let's face it, you let this thing set up, it will destroy everything on the opposing team. There are maybe a handful of mons in the meta who can switch in safely and either stall it out or retaliate. Unaware users like Quagsire and Pyukumuku laugh at Minior's Shell Smashes and while Quag can fight back with Scald/Waterfall but Pyukumuku can't really do anything in return unless Minior is in its non-Meteor form since status won't work due to Shields Down. There are a few others that can switch in but only on the Shell Smash. These mons include Bulky Jellicent, Eelektross, and Regirock. Here's some calcs to show it:
Jellicent
+2 252+ Atk Minior Acrobatics (110 BP) vs. 252 HP / 224+ Def Jellicent: 304-358 (75.2 - 88.6%) -- guaranteed 2HKO
0 SpA Jellicent Scald vs. 0 HP / 0 SpD Minior: 228-270 (87.3 - 103.4%) -- 18.8% chance to OHKO
Bear in mind, Minior will go down if it came in on rocks since Scald does 87% minimum.
Eelektross
+2 252+ Atk Minior Acrobatics (110 BP) vs. 252 HP / 0 Def Eelektross: 198-233 (52.9 - 62.2%) -- guaranteed 2HKO
252+ SpA Eelektross Volt Switch vs. 0 HP / 0 SpD Minior: 326-386 (124.9 - 147.8%) -- guaranteed OHKO
Eelektross can EQ and can possibly prevent Minior from setting up if Eel comes in on a bad predicting EQ. 1 Volt Switch takes it out and a +2 Acrobatics just does over half on Eel.
Regirock
+2 252+ Atk Minior Earthquake vs. 252 HP / 56+ Def Regirock: 192-226 (52.7 - 62%) -- 99.6% chance to 2HKO after Leftovers recovery
0 Atk Regirock Rock Slide vs. 0 HP / 4 Def Minior: 242-288 (92.7 - 110.3%) -- 56.3% chance to OHKO
As with Eelektross, Regirock can wall Acrobatics just like Eel walls EQ. 1 Stone Edge will OHKO with or w/o rocks while Rock Slide has a good chance to OHKO w/o rocks or will with rocks.
Let's just give a warm round of applause to and welcome back this annoying slug. This thing may have hard time readjusting to this meta given how common Grass types are. It should nonetheless still find a place for itself here as a Toxic user that has access to Recover to stall out would-be sweepers. It does face some competition from Quagsire since it does the exact same thing but there are a few mons that it can stand up to like Specs Jellicent, Skuntank and Pom Pom. Scald and Earth Power do continue to help it for mons like Aggron but are completely walled by Eelektross which should see an increase in it's viability due to the fact that it can stand up to both of these drops.
Jellicent
+2 252+ Atk Minior Acrobatics (110 BP) vs. 252 HP / 224+ Def Jellicent: 304-358 (75.2 - 88.6%) -- guaranteed 2HKO
0 SpA Jellicent Scald vs. 0 HP / 0 SpD Minior: 228-270 (87.3 - 103.4%) -- 18.8% chance to OHKO
Bear in mind, Minior will go down if it came in on rocks since Scald does 87% minimum.
Eelektross
+2 252+ Atk Minior Acrobatics (110 BP) vs. 252 HP / 0 Def Eelektross: 198-233 (52.9 - 62.2%) -- guaranteed 2HKO
252+ SpA Eelektross Volt Switch vs. 0 HP / 0 SpD Minior: 326-386 (124.9 - 147.8%) -- guaranteed OHKO
Eelektross can EQ and can possibly prevent Minior from setting up if Eel comes in on a bad predicting EQ. 1 Volt Switch takes it out and a +2 Acrobatics just does over half on Eel.
Regirock
+2 252+ Atk Minior Earthquake vs. 252 HP / 56+ Def Regirock: 192-226 (52.7 - 62%) -- 99.6% chance to 2HKO after Leftovers recovery
0 Atk Regirock Rock Slide vs. 0 HP / 4 Def Minior: 242-288 (92.7 - 110.3%) -- 56.3% chance to OHKO
As with Eelektross, Regirock can wall Acrobatics just like Eel walls EQ. 1 Stone Edge will OHKO with or w/o rocks while Rock Slide has a good chance to OHKO w/o rocks or will with rocks.