This is non-negotiable for the keyword "new." The save file should have 0 badges, 0 hours on the clock (or under 1 hour), and no Pokemon registered as "seen" in the Pokedex except the starter.
Writing a save to a genuine Emerald cartridge can sometimes trigger the Berry Glitch or RTC issues. Back up your original save first. pokemon emerald all pokemon save file new
Because the game is "new," you won't have HMs like Surf or Waterfall yet. The save shouldn’t break progression. However, including infinite-use TMs (like TM26 Earthquake) in the bag is a common courtesy tweak. This is non-negotiable for the keyword "new