If you are looking to play this, you will need a Nintendo DS emulator (like DeSmuME or MelonDS) or a compatible flashcart for original hardware.
It looks like you’re referencing a filename for a (the (U) indicates the US version), packed in a .rar archive, with (xenophobia) likely being a release group tag or a custom note from the uploader. 4780 - pokemon heartgold %28u%29%28xenophobia%29.rar
Specifically designed to run without freezing on NDS emulators and older flashcarts. If you are looking to play this, you