Modern Emerald Settings: Every Option in the New Game Menu

Everything is chosen at Birch's speech when you start a new game, and most of it is locked in for the run. You can check what you are playing with at any Pokémon Center PC by opening CHALLENGES.

Gamemode

Classic or Modern presets, or a fully custom set. Classic keeps the vanilla feel; Modern turns on the modern encounter tables, physical/special split, type chart rebalance, modern typings and the QoL batch. This is the single decision that shapes the rest of the run.

Features page

QoL toggles, including a fake RTC for flashcards and emulators without a real-time clock — with that on, one real hour becomes one in-game day, so daily events and night evolutions still work. Double-speed battles, following Pokémon, item drops, nickname changes and the rest live here.

Randomizer

Built into the game, not an external tool: wild Pokémon, trainers, items and more, configurable in-game. There are two ways to use it — a full randomizer run from the start, or the option to randomize only after beating the game.

Nuzlocke page

Easy, Normal and Hardcore presets, plus individual rules. See the nuzlocke guide for the full setup, but the options include level caps, player items, trainer items, party limits, EXP multipliers, catch rate and a "less chance of running away" setting.

Difficulty page

Lock difficulty — locks the selection made at Birch's speech so it cannot be changed in-game. Hard always sets Set battle style. Beating the game disables the lock.
Number of party members — a limit from 1 to 5.
Level caps — Normal caps or Hard caps.
EXP multipliers — ×1, ×1.5, ×2 or ×0.
Catch rate — ×1, ×0.5, ×2 or ×3.
Hard mode Experience — reverts the 40% EXP reduction Hard mode applies.
Less chance of running away — makes fleeing unreliable.
Player items and trainer items — whether either side can use items in battle.

Challenges page

Pokécenter challenge — play without Pokémon Centers, with PC doesn't heal enabled by default alongside it.
Ultra expensive challenge — prices multiplied ×5, ×10 or ×50.
Evolution limits.
One type only — catch a single type.
BST equalizers — normalises team strength.
Mirror Mode and Mirror Mode Thief.

Turning challenges back off

A new NPC in the Battle Frontier Pokécenter lets you disable challenges you enabled on an existing save — Evolution Limit, Mirror, Mirror Thief, Limit Difficulty, Pokémon Faint, One Type, Party Limit, Pokécenter Challenge, No Items (Player) and No Items (Trainer). You do not need a new save to escape a challenge that turned out to be a mistake.

What you genuinely cannot change is the encounter mode, the type chart option, the physical/special split and Fairy — those are read at new game and never revisited.

Option lists from the hack's official documentation and PokeCommunity feature list; cap numbers from the extracted src/caps.c data.