Modern Emerald Quality of Life: Every Change That Saves You Time

A lot of what makes Modern Emerald worth playing instead of Emerald is not content at all — it is the time you get back. Here is what changed.

Battles

• ×2 battle speed and faster-paced battles, both optional in the options menu.
• Faster battle intros.
• Press START while selecting a move to open a submenu describing it.
• 3 beeps at low health, then it stops.
• Trainer class-based Pokéballs, so you can tell who threw what.
• Catching gives EXP, as in later generations.
• Choose L+R+A or B to enter wild battles — your pick.

Overworld and encounters

• Item Drops — held items come to you when you defeat a wild Pokémon, so no Thief and no catching.
• Following Pokémon, optional, with a second option allowing big followers like Rayquaza.
• Unique surfing animations, optional.
• Shuckle makes Berry Juice again.
• Escape Rope and Dig can be banned in dungeons if you want the restriction.

Pokédex and UI

• A new Pokédex with a Stats page — the important information is in-game, including the evolve data, so you do not need an external site to check a method.
• The Pokédex tracks caught shinies, and scrolls fast: hold left or right, and hold R to scroll faster still.
• Faster trainer transitions ported from Fire Red.
• Name your rival, and switch between the Emerald, Ruby and Sapphire outfits with the Outfit Box from your mother.

TMs, tutors and moves

• Reusable TMs is a choice, not a given. On: tutors are repeatable for a fee. Off: one-time tutors, and every TM is purchasable at the Battle Frontier PokéMart.
• Nature mints after the fourth gym (or the Champion, if you did not enable them) let you fix a nature without re-breeding.
• Hidden Power shows its type, and does a flat 60 damage.

The ones that change how you play

The Stats page in the Pokédex is the biggest one, because it puts evolution methods and base stats in the game itself. Item Drops is the second, because it makes held items a reward for battling rather than a Thief mini-game. Reusable TMs is the third, and it is genuinely a fork in the road: pick it based on whether you want convenience or a reason to care about TMs.

Feature list from the official Modern Emerald documentation and the hack's PokeCommunity feature list.