Pokémon Campaign is a Flash game set in the Pokémon world, but allows for open-world exploration and real-time combat. Catch and level Pokémon, explore new areas, and take on missions in the all-new Campo Region!
One of my favourites from the first generation, Rhyhorn, is available in Mt. Payne! Its defenses are tough to break through.
Also, looks like I found where Magnemite moved to since Demo 0.2! It can also be found at Mt. Payne.