At the very start of Pokémon HeartGold, when you first can leave New Bark Town and wander south, Route 46 only has three wild Pokémon :

  • Rattata
  • Spearow
  • Geodude

These are all low-level (around levels 2–4) and appear in the grass as you begin your journey.

Quick details

Wild Pokémon in Route 46 (Start of HeartGold)

Pokémon Where Typical levels (start of game)
Rattata Grass (high grass) 2–4
Spearow Grass (high grass) 2–3
Geodude Grass (high grass) 2–3
Their encounter rates vary by time of day (morning/day/night), but the species list stays the same at the start of the game.

What this means for your early game

  • These are some of the very earliest Pokémon you can catch in HeartGold, along with the ones on Route 29.
  • If you’re looking for a Geodude early (useful for Rock/Ground coverage and HM moves later), Route 46 is one of your first spots.
  • You do not need to go through Route 46 immediately to continue; the game is designed for you to go east to Route 29 and then to New Bark Town’s lab first. But if you backtrack south, you’ll find this route and its small wild population.

Extra notes (later in the game)

Once you get further into the game and can access more areas (like shaking trees or using Hoenn/Sinnoh music for special encounters), Route 46 can have additional Pokémon such as:

  • Spearow (also in trees)
  • Aipom (Headbutt trees)
  • Heracross (Headbutt trees in some versions)
  • Special Hoenn/Sinnoh sound-based Pokémon (like Posipi/Negapi, Lixy, etc., depending on music)

But these are not part of the “at the start” list; they require items, abilities, or later-game access.

Short answer: At the start of HeartGold, Route 46 has only Rattata, Spearow, and Geodude as wild Pokémon in the grass. Information gathered from public forums or data available on the internet and portrayed here.