National Dex OU — Expert Study Guide
Format:
gen9nationaldex(Gen 9 National Dex OU) · Snapshot: 2026-05 (usage = Smogon 2026-04,gen9nationaldex-1760, 613,590 battles) Audience: experienced/expert players. This guide skips fundamentals — no “what is a pivot,” no type-chart 101. Reader goal (this build): learn to teambuild aggressive Offense — explicitly not bulky offense, not hyper offense. See06-building-offense.md.
Format in one line
National Dex OU keeps OU’s full National Dex movepool plus Mega Evolution (1 per team, Mega Clause) plus Z-Moves (1 per team), and keeps sleep moves legal (unlike Gen 9 OU). Mega + Z-Move are your only “extra” mechanics.
Because typing is permanent here, defenses are reliable — a wall that checks your breaker on paper checks it on the field. That is why the meta is dominated by Bulky Offense and Balance (resilient cores that pivot, chip, and grind win a stable long game), and why pure offense is viable but demanding: it out-sequences walls (hazard pressure + dual breakers sharing no checks + speed control) rather than brute-forcing them.
Coming from Gen 9 OU, or importing an old set? See Appendix: The Tera Ban — the rule, the set-legality checklist, and what’s different.
Meta thesis (2026-04)
The format sits on a small number of load-bearing pillars and a wide tail of matchup picks.
- S-rank — the two you build around or against:
- Gholdengo (20.42% usage) — Ghost typing makes it the premier spinblocker, while Good as Gold makes it immune to targeted status-category moves such as Defog/Toxic; Nasty Plot + Make It Rain (+ Steelium-Z) turns hazard control into a wincon. It single-handedly props up hazard-stack offense.
- Zamazenta (19.67%) — the best physical wall-breaker/setup pivot in the game at 412 Speed (base-138 max+), Body Press + Iron Defense flips it into a wincon vs teams that lack special pressure, Haze/phazing, or Unaware counterplay.
- A+ glue you will see constantly: Alomomola (24.40% — #1 usage, Regenerator Wish-pivot wall), Landorus-Therian (19.53%, SR/U-turn/Intimidate glue), Zapdos (14.67%, Defog/Volt pivot), Kingambit (14.27%, Supreme Overlord cleaner), Dragonite (14.12%, DD + Multiscale + priority), plus Ogerpon-Wellspring, Slowking-Galar, Tapu Lele, Toxapex, Garchomp, Diancie-Mega.
- The flex layer (A / A-): Great Tusk (13.87%, the format’s hazard-control glue), Gliscor (15.82%), Terapagos (17.33%, Tera Shift — see below), Ting-Lu, Urshifu-Rapid-Strike, Kyurem, Charizard-Mega-Y, Iron Treads.
- High-usage offense engines the council ranks lower (B+): Iron Valiant (12.33%), Raging Bolt (12.29%), Scizor-Mega (8.80%) — ubiquitous on offense, ranked down for inconsistency / single-Mega-slot competition. They get full pages anyway because you will use them.
Terapagos footnote (it matters): Terapagos is legal and plays as Terapagos-Terastal (BST 600, Tera Shell) via its Tera Shift ability on switch-in. See its threat page and Appendix: The Tera Ban for why the ability is fine here.
How to read this guide
| File | What’s in it |
|---|---|
01-mechanics-natdex.md | The mechanics that define NatDex: Mega/Z rules, Future Sight, Good as Gold / Magic Bounce, Booster Energy, legal sleep, the banlist headline. |
02-viability-tiers.md | The master tier table — VR-led, 2026-04-usage-annotated — with notes on the ~5 places usage and VR disagree. |
03-top-threats/ | 24 full threat pages (S/A+ down through the format-defining B+ engines). Each closes with an offense angle: run it, or break it. |
04-archetypes.md | The archetypes, Offense first — Offense vs Bulky Offense vs Hyper Offense defined precisely — then Balance, BO, HO, Sun, Sand, Rain, Stall. |
05-common-cores.md | The reused functional cores, offense cores foregrounded, grounded in official 2026-04 teammate data. |
06-building-offense.md | ★ The teambuilding centerpiece. How to actually build aggressive offense: skeleton, speed control, momentum/pivot chains, hazard pressure, breaker selection, a step-by-step build, and the common ways offense folds. |
07-sample-teams.md | Vetted sample teams with pilot notes, offense teams first, each with “how to build/adapt this.” |
08-speed-tiers.md | The benchmarks that decide turns: the 412 Zama wall, Scarf lines, +1/+2 control, Booster lines. |
09-matchup-matrix.md | Threats × archetypes/checks grid — who beats who at a glance. |
10-glossary.md | Terse glossary + abbreviation key (only the non-obvious terms). |
Suggested path for the reader’s goal: 01 → 04 (what offense is and isn’t here) → 05 (the cores you’ll snap together) → 06 (build one) → 07 (study working examples) → use 03 and 02 as reference while building.
Conventions
- Tiering spine: placement follows the Smogon NatDex OU Viability Rankings (thread OP last edited 2026-05-19); each entry is tagged with its 2026-04 weighted Usage%. Where the two disagree, the entry keeps its VR slot and gets a one-line “why.”
- Usage numbers are the weighted Usage% column (not Raw% / Real%). Unresolved tail figures are marked
~local; a few outside-top-30 figures are filled only where later audit notes resolved the exact 2026-04 line. - Mega = 1/team, Z-Move = 1/team. Corkscrew Crash appears only as the Z-output of Steelium-Z + Make It Rain — never as a chosen move.
- Freshness: this is a 2026-04 snapshot. Each section is organized to be re-run against a newer usage month without rewriting the structure.