Honestly, I think the perfect ending that Gamefreak could use would be the Poke Park 2 engine. It’s so vibrant and colorful, and the models look absolutely amazing. It’d be the perfect engine to do Pokémon games in.
Let's Go Pikachu and Eevee's engine is solid, and Coliseum/Gale of Darkness was a pretty solid attempt at moving 2D to 3D back on the GC. I had a good time with Alpha Sapphire but preferred the art style of Let's Go more.