You can sweep with any Pokemon if your opponent isn't good at the game. However, if we assume that your opponent is at least somewhat good at the game, then we can analyze a bit deeper.
Let's look at Minior's stats. In Meteor Form, its only remarkable stats are its defenses, at base 100 each. Everything else is a measly sixty. This should allow it to get a Shell Smash off relatively easily, but things aren't quite that simple. Sure, it gets a Shell Smash off. Now what? It still has unimpressive HP, which will only drop further when Shields Down is activated, along with a drop in both defenses as well. It's indeed fast, as well as having high attacking stats when Shields Down activates, but it has a very poor defensive typing, and is weak to five common types. It can easily be revenge killed, and it's way out of its league in AG, where legendaries run rampant.
It has five weaknesses. One is Steel. Zacian-Crowned is one of the most popular Pokemon in NatDex AG, so Minior is almost certainly going to be OHKOed by STAB +1 Behemoth Blade. Dusk Mane Necrozma is also extremely common in the tier as well. Zygarde can destroy Minior with Thousand Arrows, and its other weaknesses are very exploitable as well. Primal Kyogre runs Ice Beam 95% of the time, and Primal Kyogre is used on roughly 9% of NatDex AG teams. Minior is also weak to Primal Kyogre's STAB Water moves, which also get a boost from rain. Tyranitar is somewhat common on NatDex AG teams as well, and it runs Rock Tomb 82% of the time. A great many Pokemon (Xerneas, Kyogre, etc.) also run some form of Electric move, which will very likely eliminate Minior from the field within an instant.
Minior isn't a good Pokemon in NatDex AG at all. It's weak to common types, and its poor defensive typing means it can and will be OHKOed a lot of the time. It may be able to find a use in lower Generation VII tiers, but that's about it.
Pikalytics
Smogon stats
Hope I helped!
