True, M-zam used to be BL, but upon retesting, it came back to UU.
For starters, Zam and M-Zam's counters/checks are pretty much the same:
- scarfers (whose base speed stat must be above 85 for mega)
- even if not very common, priority
- special walls bar blissey and even some physically defensive mons (rotom-h, gligar), since psyshock is more common
- half of the entire fucking tier that is slower than it, yet bulky enough (they can live at least one hit and OHKO back, unless regular zam and sash)
Also, hate to break it to you but CM M-Zam isn't really a thing. I have seen very few people run it and these few I came across were more than enough to conclude that it doesn't work at all. In most cases, M-Zam has no chances of setting up, given how frail it is. You'd have to rely on very specific situations like, for example, a Blissey OHKOing a mon and you sending M-Zam in to set up on it, and even then, the sweep would be easily stopped by a reliable scarfer, because scarfers are VERY common nowadays on UU. They were already quite necessary, and now with the tier being dominated by newly introduced oras megas like M-Lopunny and M-Beedrill, they're more needed than ever. This brings me to my next point:
- M-Zam is NOT supposed to be a set-up sweeper, it acts much better as a revenge killer. Thanks to its high speed and spa stats, it's guaranteed to KO anything that's been weakened enough.
However, this also applies to regular Zam. In fact, I personally think Zam is better than it's mega. They're both better suited as revenge killers, and in that regard, regular Zam has two strong points its mega doesnt:
- Focus Sash/Life Orb in conjunction with Magic Guard, and I don't think I even need to explain much why this is great/makes it superior to its mega.
Speaking of UU and revenge killers, here's a thing I think needs to be suspect tested, at the very least: M-Beedrill
- it's too fast for the tier (only M-Zam and certain scarfers outspeed it)
- it's a glass cannon (150 base attack + adaptability)... except the glass part is practically irrelevant in most situations. why? because u-turn, thats why. not to mention that it makes M-Beedrill an incredibly good revenge killer... or killer in general actually, since it can OHKO a ton of mons in UU anyway, it can do massive damage while avoiding getting hit at all
- finally, getting rid of M-Beedrill's counters is way too easy, due to the aforementioned u-turn. all you have to do is send it in and spam u-turn, and slowly, you're able to weaken most of its counters (donphan, m-aggron, hippowdown, swampert,...) while bringing in a counter/check yourself to bait them out
In general I feel like it's too easy to play M-Beedrill. Building a team around it consists of having checks for its counters, a physical/special wall core for scarfers, hazards and a spinner/defogger. OU/BL is the tier where it truly belongs.
Here's the most common set people run:
Beedrill @ Beedrillite
EVs: 252 Atk / 4 SpD / 252 Spe
Jolly Nature
- U-turn
- Poison Jab
- Knock Off/Drill Run
- Protect
Another one I think should get suspected is M-Gallade, though, I'm gonna wait to see people play it more. It seems like it's not getting enough usage, surprisingly. For now, I won't bother with it much, I'll just wait until everyone realizes how good it actually is, and starts spamming it, since that's how things usually get banned.