Pokemon Emerald, just the story.
First game to 100% complete?
Other then the unreachable pokemon through cheats and Mystery Gift (I got all except the two that were unavailable for like two years -.-, and I had bought the game after) was Pokemon Black. Every little thing was completed, unlocked that tree in the secret garden, completed National and Regional Pokedex and all. Every pokeball gotten, (didnt look at a walk through of those, may of missed a few.) Hidden items taken, trainers battled and storyline completed. Oh, also my party was full lvl 100's Eevee trained.
Also, did it on both black and white. I did pkmn black my brother did white. Both were completed completely, and legit. Damn, that was a while ago. I ended up losing the game cartridge, along with my dark-shiny requaza, which was saddening.