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.
Defenses are reliable here. 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.