It sounds like you're referencing a few different things that don't actually exist as a single product. Let me clarify:
What you are likely looking for is the infamous Pokémon Emerald "Ultra Trashman" ROM Hack, a notoriously difficult and hilarious modification of the 2004 classic. The "1986" tag often refers to the style of old-school, punishing difficulty reminiscent of NES games from that era, or simply a community meme regarding the version number. 1986 pokemon emerald utrashman rom free
1986PokemonEmeraldUTrashMan directory listing - Internet Archive It sounds like you're referencing a few different
Free ROMs: A Gray Area
This is a fascinating premise—a "lost" 1986 version of Pokémon Emerald (which originally launched in 2004) suggests a glitchy, retro-futuristic aesthetic. The 8-Bit Emerald retro-futuristic aesthetic. The 8-Bit Emerald