I want to share with you some ideas that I had recently.
Making fangames that are based on Japanese Pokémon games that never arrived in Europe / outside of Europe and other Pokémon games like Pokémon e-Cards, Pikachu ga Pokeboru aishimasu, and other spin-offs like Pokémon Mystery Dungeon, Pokémon Ranger, and Pokémon Quest.
Try to mix Pokémon with other games... I had this idea when The Sims 4 had a cross over with Star Wars. Many people liked the cross over and they said that it goes well within the game. So for this to work, the Pokémon game should have all the important aspects of a Pokémon game and many important factors about the other game. For example, if it would be a Pokémon + DragonBall game, it should have Dialogue, no Pokéballs but it should have: fight, cutscenes, dragon balls, the same currency they use in DragonBall, and all items should be based on drinks and food that are available in the series.
Open world: making your Pokémon fangame an open-world game, should have some important questions to answer: "Do I want to add badges in my fangame?", "If yes, how many badges should my fangame have?", "How can I prevent the player from going from A to B, when he doesn't have the right badge?". Don't add NPC's saying that the player can't walk there, try to make your game as natural as possible.
Make Pokémon fangames based on real-life countries. Before adding fakemons: Research about the animals that live in this country. Draw your fakemons on a paper before spriting it on your computer. Your fakemons should be based on those animals that live in that country. Try to make Hi-res sprites of your fakemons! Your game will look more cleaner with Hi-res sprites, Hi-res tileset, and big NPC's and PCs. Add customization to your fangame and try to represent the fashion of that country. Write your plot based on that country. Research the mythologies about that country, add a library with real poems about that country, add some easter-eggs to your fangame that represents that country. Etc.
That's it for now, if I have more ideas I may edit this and add more ideas to it if it's ok for you.
Making fangames that are based on Japanese Pokémon games that never arrived in Europe / outside of Europe and other Pokémon games like Pokémon e-Cards, Pikachu ga Pokeboru aishimasu, and other spin-offs like Pokémon Mystery Dungeon, Pokémon Ranger, and Pokémon Quest.
Try to mix Pokémon with other games... I had this idea when The Sims 4 had a cross over with Star Wars. Many people liked the cross over and they said that it goes well within the game. So for this to work, the Pokémon game should have all the important aspects of a Pokémon game and many important factors about the other game. For example, if it would be a Pokémon + DragonBall game, it should have Dialogue, no Pokéballs but it should have: fight, cutscenes, dragon balls, the same currency they use in DragonBall, and all items should be based on drinks and food that are available in the series.
Open world: making your Pokémon fangame an open-world game, should have some important questions to answer: "Do I want to add badges in my fangame?", "If yes, how many badges should my fangame have?", "How can I prevent the player from going from A to B, when he doesn't have the right badge?". Don't add NPC's saying that the player can't walk there, try to make your game as natural as possible.
Make Pokémon fangames based on real-life countries. Before adding fakemons: Research about the animals that live in this country. Draw your fakemons on a paper before spriting it on your computer. Your fakemons should be based on those animals that live in that country. Try to make Hi-res sprites of your fakemons! Your game will look more cleaner with Hi-res sprites, Hi-res tileset, and big NPC's and PCs. Add customization to your fangame and try to represent the fashion of that country. Write your plot based on that country. Research the mythologies about that country, add a library with real poems about that country, add some easter-eggs to your fangame that represents that country. Etc.
That's it for now, if I have more ideas I may edit this and add more ideas to it if it's ok for you.