5. The Everstone
Evolution is one of the most integral parts of the pokémon games. With a few simple levels, your pokémon will transform from a puny pile of crap to a fire breathing beast of death. Unless, of course, it's equipped with an Everstone: An item that allows your pokémon to level without the strain of becoming too useful.
The Everstone made its first appearance in Pokémon Gold and Silver as the second prize in the bug catching contest (and considering first prize was a Sun Stone, you should probably work a bit harder next time). Stopping pokemon from evolving can allow it to level faster and learn moves earlier, so the Everstone seems useful on the surface. However, pressing "B" does the exact same thing. And you don't have to be runner-up in some stupid bug contest. Then again, you wouldn't want to strain your thumb reaching for the "B" button.
4. The VS Recorder
Not to be confused with the VS Seeker, the VS Recorder is a device that allows you to record your battles. What's the in-game benefit of it? There isn't one. You get no experience, no cash, no items, NOTHING. The VS Recorder is used exclusively for players to smugly show off their mad skills as a pokémon trainer. Essentially, all they're doing is showing their lame battle to an audience that will undoubtedly just find fault in their technique. Beats going outside, I guess.