For pokemon that have been buffed over the gens, I'm surprised this guy hasn't come up yet (although I was waiting for the evolution confirmation):
Magnemite in Gen3 was a decent mid-game addition. Evolved right after you got it, excellent typing, good gym match-ups to finish the game with. The problem was it's movepool is bone dry except for electric.
What's changed? Well, it got this guy:
and some movepool upgrades. Mirror Shot and Flash Cannon give it a secondary STAB to work with (and fairies give it something to hit it with), and the physical/special split means Tri-Attack is now workable. On support it gets magnet rise, patching that 4x ground weakness when you need it (which you might, I remember Winona's Altaria and Tate & Liza surprising me with Earthquake in Emerald). Still barren overall, but you've at least got just enough to work with now.
It also had some ability buffs. For the most part, Magnet Pull is great in Metagame, but useless in-game. Sturdy however gives it an auto-focus sash, and in-game everyone has a recovery move (the item bag! Your unofficial 7th pokemon!).
Now we don't know when or where Magnezone will show up yet, but we do know one thing: Eviolite. Might be worth not evolving to keep Magneton the super-wall around.
Bottom line, this guy is one slick chrome ride to the Elite Four once you get to New Mauville.