I used Shuckle as a wall for a good 2 months (though now replaced by Eviolite-Chansey), and also as a phazer Scrafty. This guy gets to 300 in both Defensive stats with the right investment, can absorb status with SS and phaze with Dragon Tail. Winner!
Soul Silver Pokedex: 493 seen, 493 caught
Battle Factory record: 33 wins, 29 trades.
Battle Tower record: 42 consecutive wins with 12 attacking team of: Infernape, Latios and Metagross. If only I could get at least 7 more...