It looks like a dragon type is your answer
Why dragons? Dragon type moves are only resisted by steel types. As such, most Pokemon are hit hard by STAB alone. As for steel types, they can be easily covered by fire, fighting, and ground coverage moves. Many dragon types are also very powerful, and here's a couple choices who you may enjoy, both of which are available in game in all gen five games, with no dream world, poketransfer, or hidden grottoes requires
Ability: inner focus (if you have access to it use multiscale)
Brick break/super power
Dragonite loves a speed and attack boost, and dual screens augment his already impressive bulk. He is somewhat slow without a speed boost however. He has extremepeed as a breeding move, but it is hard to get. He can also go mixed if you desire.
Option number two
Draco meteor/ dragon pulse
Focus blast/ super power
This guy takes the special approach, but like dragonite can also go mixed to suit your needs.
He is faster than dragonite but still isn't that fast, and will love and speed and nasty plot boosts you give him.
One note: the main flaw to my advise is ice shard, a super effective priority which will almost always take out dragonite and if hydreigon is weakened a bit remove him as well, but this is rare in game, though in compatible battles its pretty common