Here's an example of a Pokemon game implemented as a single HTML file with JavaScript:
To play the game, open this HTML file in a web browser and follow the prompts. The game will ask for your name and present options for actions such as going to the Pokemon store, fighting Gary, going into the forest, and checking your inventory. You can make selections by entering the corresponding number or by pressing "Enter" and typing your choice. The game will respond accordingly to your inputs. Note that this is a simplified example and does not include full gameplay mechanics or graphical elements, but it provides the basic structure for a text-based Pokemon game.