I think this one is particularly noteworthy as its looks don't match what it can do.
I mean, look at that. What the shit is that?
Well, that's its form at above 50% hp. It's a relatively tanky wall but with amusing typing in rock / flying. Not the hardest to kill thing out there when it comes to stats but fairly annoying nontheless. However, it has an amazing ability in that in that form, it's literally immune to ALL status. If I'm correct, the only "status" that works on it in that form is forcing it to switch out with roar or whirlwind or something like that. I think you might be able to swap its items as well but that might not be wise as you'll see in his second form.
At under 50% hp, Minior changes from a wall to a sweeper. Again, the stats aren't anything particularly special but they're balanced and they're optimized. It has 100 in both attack and special attack along with a new 120 in speed. It now loses its immunity to status as well. However, if it ever goes back up above 50% hp, it returns to the previous form.
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So what's so special about it?
This thing gets shell smash.
So think about it, the only way to stop this thing from getting shell smash off is to either kill it with a really powerful wallbreaker before it can get it off, or phase it out. You can't paralyze or burn it. You can't slowly chip it down. Basically once it shows up, it's almost guaranteed to get shell smash off. Additionally, because of its typing and moveset, it has amazing coverage. Since shell smash and its stats buff both special attack and regular attack, you can give Minior either Power Gem or Stone Edge, Earthquake, or even Acrobatics which becomes pretty ludicrious with white herb.
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Weaknesses?
Yeah, at first glance this thing looks incredible but it's important to realize it has a lot of interesting flaws as well. For one, it's not actually THAT tanky. This isn't a Regigigas. You can easily destroy this thing OHKO with a wallbreaker's waterfall, thunderbolt, or something like that even in shields down form.
Additionally you need to carefully choose to to invest your stats. You can't buff all its defenses as well as its offenses and its speed so your Minior will be weaker than others in some form or another, whether you choose to make it more fragile or make it hurt less.
Furthermore, it doesn't actually hurt THAT much either after a single shell smash. Hell, when you're still in shields up form, it basically just becomes a normal attack. It's hard to OHKO anything that isn't weak to its moves with this by itself. You're looking at 2HKOs at best for everything when it comes to just attacking them normally.
Lastly, it gets completely boned by priority moves. Hell, if there's a STAB Bullet Punch or Water Jet on the field you might as well not even use it.
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In any case, I thought it was a very interesting Pokemon with a powerful ability.
It's probably one of the stronger revenge sweepers in the game right now, as if it shows up when your priority users are dead and your team has all taken chip damage here and there... you're in serious trouble. Out of all the Pokemon (that aren't bullshit) that can show up last in a team battle, this one is pretty up high on the warning list.