A Scrafty should be able to power through 3 out of the Elite 4. Especially N's Scrafty, if you have Memory Link available.
And pretty much anything with good Sp. Atk and a Psychic-type move should take care of Marshal quite easily. --- The World Ends With You 2 in 2012? I sure hope so! Official Shiny Victini of the Pokemon B/W 2 and PMD: MMM boards.
I had an Arcanine with Flare Blitz, Outrage, Thunder Fang and Crunch that just decimated the two of the Elite Four and especially the champion. You may want to give that a shot. --- XBox Live Gamertag: John41617