NPC over the grass in Viridian Forest
The NPC over the grass in Viridian Forest is a natural glitch in Pokémon Yellow.
File:NPC over the grass in Pokémon Yellow.png
In the Viridian Forest, there are a girl whose sprite it's clearly over the grass. This sprite won't get off, because this trainer doesn't have range of vision, so if you want to fight, you have to talk with her. This trainer was included in Pokémon Yellow, so she doesn't appear in Red/Blue.
Video demonstration
| |