Appendix — The Tera Ban (and what changes vs Gen 9 OU)

Who this is for. If you’re coming from Gen 9 OU, or you’re importing a set built for a Tera-legal format, read this once. The rest of the guide describes the metagame as it actually plays — without Terastallization — and never re-litigates the ban. This page is the single place that states the rule, lists the set-legality consequences, and explains how the ban reshapes the top of the tier.

The rule

gen9nationaldex runs Standard NatDex + Terastal Clause: Terastallization is banned. Internally the format sets canTerastallize = null, so the action simply does not exist — there is no Tera button, no Tera type, no Tera Blast. Typing is permanent for the entire game.

Everything else National Dex is intact, plus the two extra mechanics the rest of the guide leans on:

Mega Evolution — legal, 1 per team (Mega Clause).
Z-Moves — legal, 1 per team.
Sleep moves — legal (unlike Gen 9 OU): Spore / Sleep Powder / Hypnosis are real tools.

So here, Mega + Z-Move are your only “extra” mechanics — budget them like hazards.

What the ban changes (vs a Tera-legal format)

Four things you can do in Gen 9 OU and simply cannot do here:

No defensive Tera to brick a super-effective hit or shed a weakness. A 4× weakness is a 4× weakness; a mon that loses to a coverage move just loses.
No offensive Tera to break the wall that’s supposed to stop you. The check stays a check.
No Tera Blast surprise coverage — movesets are honest and scoutable.
No STAB-on-demand — damage output is fixed by the mon’s real typing.

The one strategic consequence the whole guide follows from: because typing is permanent, defenses are reliable. A wall that checks your breaker on paper checks it on the field. That’s why the metagame is dominated by Bulky Offense and Balance — resilient cores that pivot, chip, and grind win a stable long game — and why pure aggressive Offense is viable but demanding: it has to win by sequencing (hazard pressure + dual breakers that share no checks + layered speed control), not by a one-button matchup flip. Your revenge insurance comes from Choice Scarf and priority, never a type-change.

Set-legality checklist — run every imported set through this

Sets copied from a Tera-legal source carry illegal lines. Before you lock a build:

Delete any “Tera Type” line. Treat the mon’s printed typing as fixed.
No Tera Blast, no defensive type-flip, no “Tera-to-dodge-the-revenge” plan. All dead. Replace any Tera-revenge insurance with Choice Scarf or priority.
Ogerpon-Wellspring’s Embody Aspect is Tera-only → DEAD. Without Terastallizing it gets no +1 SpD boost and stays in base form. It is strictly a Water-Absorb fast SD wallbreaker / pivot: Ivy Cudgel / Power Whip / Swords Dance / Knock Off, Wellspring Mask (×1.2 to all moves), base-110 Speed. Any set selling a “+Def/+SpD Embody-Aspect snowball” is wrong for this format.
Item-locked Megas hold nothing else. Diancie-Mega (Diancite), Charizard-Mega-Y (Charizardite Y), Scizor-Mega (Scizorite), etc. consume the item slot — no Z-Crystal, no Heavy-Duty Boots, no Choice item — and they spend the team’s single Mega.
Corkscrew Crash is a Z-output only (Steelium-Z + Make It Rain), never a chosen move.
Dragonite’s Extreme Speed is +2 priority, not STAB here — there is no Tera-Normal to make it STAB.
≤ 1 Mega and ≤ 1 Z-Move on the team; no banned ability/item/move.

The one legal “Tera”: Terapagos

Terapagos is legal and a real A-tier threat. It plays as Terapagos-Terastal (BST 600, Tera Shell) via its Tera Shift ability on switch-in — this is an ability that triggers automatically, not the banned Terastal mechanic, and it costs no Tera action. Its Stellar form (BST 700) is unreachable, and there are no Tera Starstorm / Stellar type-change lines. Don’t confuse the ability name with the banned mechanic. (Full set: Terapagos threat page.)

How the ban reshapes the top threats

The threat pages describe each mon as it plays now. For readers comparing to the Tera meta, here is the net effect of the ban, mon by mon:

Threat	Net	Why
Gholdengo	Helps	Locked Steel/Ghost can’t be exploited by a defensive type-change; opponents can’t flip type to resist Make It Rain or to brick the spinblock.
Zamazenta	Helps	Frail mono-Fighting, but its checks can’t change type to dodge Crunch / Close Combat / Body Press; its own inability to escape Moonblast or Brave Bird keeps it fair.
Alomomola	Helps (big)	Defensive cores can no longer be blown open by a surprise type, so its long-game wall job got easier — and it never wanted an offensive trump itself.
Landorus-Therian	Helps	Can’t be blown past by a surprise Ice/Water nuke flipping its 4× Ice weakness; the cores it pivots into can’t shed weaknesses either. The old “Tera-Flying Lando sweeps” line is dead — it’s pure glue/pivot.
Ogerpon-Wellspring	Hurts	In Tera-legal play it Teras Water for a free +1 SpD (Embody Aspect) and is near-uncheckable; here it stays a fast, frail, scoutable breaker.
Kingambit	Helps	Can’t be cheesed by a defensive type-flip — but neither can its checks (Great Tusk, Zamazenta) shed the 4× Fighting weakness that defines the matchup. Honest rock-paper-scissors.
Dragonite	Helps (net)	Lost a Normal/Flying ceiling, but so did every wall that flipped its typing; its Multiscale + Z-Move + priority package needs no type-change to function.
Garchomp	Pushed	Toward its multi-hit identity: Scale Shot + Loaded Dice is now the strongest way to break Multiscale, Sash, and Sturdy while raising its own Speed.
Tapu Lele	Helps (net)	Defenders can’t flip typing to brick its STAB; it never wanted a trump. Still frail and outsped → Choice Scarf does the heavy lifting.
Slowking-Galar	Helps (net)	Loses no offensive ceiling; the fairies/dragons it walls lost their get-out-of-jail typing, so its 95/110 special wall holds up.
Toxapex	Helps	Defenses are reliable, and the old “Tera Flying / Tera Fairy” tech is dead — its excellent physical-wall typing is fixed and dependable.
Zapdos	Helps (net)	Opponents can’t escape its Hurricane / Heat Wave coverage and it never needed defensive Tera. Still can’t patch its own Rock/Ice weakness — that’s its ceiling.
Diancie-Mega	Helps	Frail 50/110/110 defenses can’t be patched by a type-change on either side, so its Magic Bounce utility and scoutable mixed coverage both stay honest.
Great Tusk	Helps	No surprise defensive type-flip dodges its coverage, so its Ground/Fighting typing is more reliable; the breakers it walls lost their escape hatch.
Gliscor	Helps	Its 4× Ice weakness is a fixed liability — but so is every wall it grinds; defenses are reliable and Gliscor is among the most reliable.
Ting-Lu	Helps	Real Dark/Ground weaknesses, but opponents can’t escape the Vessel tax or a coverage move; a slow phazing Leftovers tank is exactly what a stable meta rewards.
Kyurem	Mixed	Hurts Kyurem in the abstract (no Ice/Ground type-change to brick checks) but hurts its checks more: Waters can’t shed the Freeze-Dry weakness, so it stays a clean 2×.
Charizard-Mega-Y	Hurts (mildly)	Never relied on Tera, but lost the option to shed its 4× Stealth Rock weakness — even more hazard-fragile.
Iron Valiant	Hurts	Leaned on Tera to fix its frailty and patch coverage; here it’s a glass cannon with no defensive recourse.
Scizor-Mega	Helps	Opposing breakers can’t change type away from its Bullet Punch priority; it never wanted Tera (its slot is the Mega stone anyway).
Iron Treads	Helps	No longer fears a type-flipped Great Tusk or an opponent invalidating its STABs; fixed, predictable typing teammates can build around.

(Urshifu-Rapid-Strike and Raging Bolt are roughly ban-neutral — neither leaned on Tera.)

Glossary carry-overs

Tera ban — Terastallization is illegal here (Terastal Clause). Typing is permanent; no Tera Blast, no defensive/offensive Tera. The single fact that shapes the meta.
Embody Aspect (dead) — Ogerpon’s Tera-only stat boost. Under the ban it never triggers; any Ogerpon set “promising” it is illegal. Ogerpon-Wellspring is a Water-Absorb Ivy Cudgel pivot, not a setup sweeper.