Just won the Elite Four last night, and indeed it's quite challenging. I just love the level and difficulty curve here. The fact that you can't switch makes it more harder. My team log is:
Froslass (Amanda) Lv. 72 @ Choice Specs - Crunch, Destiny Bond, Ice Beam, Shadow Ball
Stunfisk (Choco) Lv. 71 @ Quick Claw - Thunderbolt, Earthquake, Surf, Earth Power
Togekiss (Serenity) Lv. 72 @ Focus Band - Thunder Wave, Psychic, Fly, Ancient Power
Empoleon (Quentin) Lv. 70 @ Bright Powder - Flash Cannon, Scald, Power Gem, Drill Peck
Nidoking (Spencer) Lv. 70 @ Soft Sand - Superpower, Rock Slide, Earthquake, Gunk Shot
Lilligant (Lili) Lv. 71 @ Leftovers - Giga Drain, Quiver Dance, Fiery Dance, Sleep Powder
Can my team survive the rematch (if there is?). Anyway, this is a well-done hack. Good job.