Iron Bundle needs to go. I honestly think it should have been quickbanned before Flutter Mane. Water + Freeze Dry is the best two-move coverage option in the game, and it gets STAB on both. It's speed tier (136 compared to Flutter Mane's 135) also means unless you are running Dragapult, you are not outspeeding it without a scarfer or priority. On top of that, it has 114 base def, meaning you need very specific priority users, or multiple users of priority to bring it down. Flutter Mane had to commit with Tera to live priority, Iron Bundle doesn't care. Flutter Mane had to commit with Tera or other coverage to bypass it's checks (Psyshock for Clodsire, Mystical Fire for Scizor, etc...), Iron Bundle literally has no reliable checks outside of Blissey/Chansey or some fringe AV answers. I haven't even seen people use anything but Tera Ice on Iron Bundle, because it doesn't need anything creative to 6-0 teams.
CB or LO Breloom Mach Punch can OHKO, but it forces Breloom on that specific set, and forces you to press Mach Punch or else Iron Bundle OHKO's Breloom.
CB Technician Scizor Bullet Punch is a 2HKO, and Specs Iron Bundle can OHKO back, guaranteed if rocks are up.
CB Tera Water Palafin Jet Punch is an unfavorable roll to 2HKO, and Iron Bundle OHKO's back, pretty sure most Palafins are running Leftovers right now anyways.
CB Chien Pao Sucker Punch is a 2HKO, can OHKO with chip, but gets OHKO'd back by Iron Bundle.
CB Lokix cannot OHKO with First Impression or Sucker Punch and is OHKO'd back
CB Kingambit cannot OHKO with Sucker Punch until three teammates are dead (roll) or four to guarantee it. Iron Bundle OHKO's back with rocks.
Here are your only options into Iron Bundle:
1. Run CB Technician Breloom (Which can't switch in unless you make a crazy good predict. In my experience, Iron Bundle is pressing Freeze Dry 80% of the time though) to revenge with Mach Punch. Better hope they don't switch out into a Ghost so you immediately lose momentum. You can also try Vacuum Wave Lucario, since you can OHKO without having to run a choice item or even LO. There is also, CB Kingambit, but locking into Sucker Punch is even worse.
2. Run other mons with priority, but accept that it will cost two mons to revenge Iron Bundle. The mon he killed and the first priority user sent out to revenge.
3. Revenge with a slower, bulkier mon who can tank a hit. Unless that mon is AV Iron Hands, expect to be below 50% health after.
4. Revenge with a scarfer (This is your best option imo if you don't want to immediately lose to Bundle on preview)
5. Run fringe defensive options like AV Sylveon, AV Iron Hands, or Florges.
6. Run Blissey or Chansey, who are pretty trash at the moment.
Iron Bundle hits everything in the tier at the moment. Not only that, but it is one of the fastest in the tier. Most of the time Iron Bundle comes out in a favorable matchup (which is a lot considering those to previous sentences), it's a 50/50 on whether it nets a kill. The rest of the time, it isn't even a 50/50 because Freeze-Dry is just so hard to defensively prep for. In fact, prepping defensively for Bundle forces you to use unviable mons, who will just limit the capabilities of your team into every other matchup.
Iron Bundle also OHKO's a large majority of hazard setters, making it difficult to get them up in a game into him. If a player pivots in to Bundle in a matchup where he can outspeed and OHKO, it will be incredibly difficult to get any chip at all on him. This wouldn't be such a problem if Bundle didn't OHKO so many mons, making it easy to get in a situation like this.
Because of all these reasons, Iron Bundle forces you to commit too many resources just to have a fighting chance. I normally enjoy broken mons, but Bundle is so broken that I can't be creative at all in the teambuilder, it's so so limited.
This is the set I've been using, but Bundle has other options with Boots + Taunt or even 2 Attacks + Taunt + Encore:
Iron Bundle @ Choice Specs
Ability: Quark Drive
Tera Type: Ice/Fairy
EVs: 4 Def / 252 SpA / 252 Spe
Timid Nature
- Hydro Pump
- Freeze-Dry
- Ice Beam
- Flip Turn
Tera Ice let's you use 100% accurate Freeze Dry instead of Hydro Pump, when you need to ensure you'll hit. Tera Fairy is for Mach Punch, Sucker Punch and First Impression resists.