Version 3.0.0 · 2026-10-13
CHOMP decides what to do at team preview: which four Pokémon to bring and which two to lead. It reads both open team sheets and returns a mixed strategy over the 90 bring-and-lead options. It scores every pair of options with a learned win chance, then solves the resulting game exactly.
CHOMP v1 is part of ABRA. Its code is in ABRA's
solver/chomp/. It plays on the Pokémon Showdown ladder
through ABRA's live client, ROTOM. This repository holds the CHOMP documents and the retired browser tool.
Results, with sources and limits: the white paper. In short: CHOMP beats the most common human bring for a team, and it shows no clear edge over the bring a human chose after seeing the opponent.
| Component | What it is | Where |
|---|---|---|
| CHOMP v1 | The live preview solver: learned cell scorer + exact equilibrium solve + best-of-three adjustment | ABRA solver/chomp/v1/ |
| Cell scorer | P(win) for each of the 8,100 option pairs, from engine facts computed by ABRA's simulator MEDICHAM | ABRA solver/chomp/v1/scorer.js |
| SLOWKING | The exact matrix-game solver (linear program) | ABRA solver/slowking/matrix.js |
| ROTOM hook | Asks CHOMP at every preview when an arm says "preview": "chomp" |
ABRA solver/rotom/policy.js |
| CHOMP v0, v2 | Earlier and later versions that did not pass their gates | ABRA solver/chomp/, solver/chomp/v2/ |
| Retired userscript (Reg M-B) | The old Tampermonkey browser tool, versions 1.0 to 2.5.1 | this repository, app/ and engine/ |
| Document | Job |
|---|---|
| White paper | The method, the math, every figure and its source |
| Plain-English deck (PDF) | The same story for a non-specialist |
| Technical documentation | Run, test and maintain CHOMP (ASD-STE100, Diátaxis) |
| CHANGELOG | Every change |
For AI agents and search tools: llms.txt lists the key documents and files.
See the technical documentation, Part 1. CHOMP runs from an ABRA checkout with
ABRA_REGULATION=regmc.
Until 2.5.1 CHOMP was a Tampermonkey userscript for Reg M-B on Pokémon Showdown. It is retired: it targets a
retired regulation and its species data is out of date. The code stays in app/, engine/, build/ and tests/ as
history, and CI still runs its tests. Its Reg M-B validation is in docs/VALIDATION-REPORT.md.
Do not use it for Reg M-C.
- Simulator, data and training: ABRA, on the Pokémon Showdown Reg M-C format.
- Human games: the public Pokémon Showdown replay API.
Not affiliated with Nintendo, Game Freak, The Pokémon Company, or Smogon/Pokémon Showdown.
See LICENSE.