The number “4780” does not appear in the vanilla HeartGold code. However, a search through ROM hacking forums (like PokeCommunity and GBAtemp) reveals a 2015 post about a mod called — allegedly a difficulty hack where trainers’ dialogue becomes hostile based on the player’s starter origin.
It looks like you're referencing a specific Pokemon HeartGold 4780 pokemon heartgold uxenophobia hot
To survive HeartGold UXenophobia Hot , you must throw out traditional casual playstyles. Optimize Your Held Items The number “4780” does not appear in the
This is where the search query takes a dark, niche turn. "Uxenophobia" is a portmanteau of (the Legendary Psychic-type Pokémon introduced in Generation IV) and Xenophobia (the fear or hatred of that which is foreign or strange). 4780 pokemon heartgold uxenophobia hot