Speaking of double battles, Clair/Lance in HGSS Dragon's Den if you picked Chikorita. Your rival is lucky to last 3 turns, and Typhlosion will always die 1st turn. I ended up using a parafusion combo with Ampharos (Signal Beam is useful, wut?) to get past those two, because you will be on your own for the majority of the battle.
To make things worse, Clair and Lance are at their rematch levels...
But I got wiped out with no saving grace at all!
And then I'm told I don't have any talent?! Man...