While I generally actually enjoy grinding in games, the grinding involved in the Pokémon metagame is just so RNG (or attempted RNG manipulation) dependent that it's insane to even think about for me.
EDIT: OMG 100th page hi everyone.
I've personally always loved Custom Robo Arena for the DS. Plot was above average, gameplay was fun, and the concept was amazing. Definitely in my top five, and yet only the most hipster of my friends seem to know about it.