I'm remembering in RBY, when Rage worked by increasing your Attack stat... It meant your Attack would only go up six times, and even then, they were 'regular' increases (50%). However, I've noticed in GSC, Rage doubles every time you get hit. (100% increase.) That is, 20, 40, 80, 160, etc.
Even with a six-rise limit, the average damage done per turn is 210 over six turns (Double Edge is 120) and Rage outdamages Double Edge at the fifth hit. You are then cranking out 640 power Normal attacks (960 with STAB!). If there isn't a ceiling anymore, however... *shudder*
However, Rage differs from Rollout and Fury Cutter in one fairly important way- you have to be attacked for the power to double. While this shouldn't be much of a concern, you also cannot heal yourself, as this would drop the power back to 20. Thus, any Pokémon mad enough to try Rage should have very high Health, huge Defences and Leftovers equipped. (I'm thinking "Ikarilax". )
Now, it's certainly fair to assume that once your opponent sees you trying to build up a full head of steam, they will run for their BPer or other such chargeup type. This is where Berserk Gene may come in handy. You should hit yourself once or twice, and your opponent would likely feel more confident about attacking you as well. You are also 'effectively' doubling the power, so it goes 40, 80, 160, etc. (Remember, this Confusion wears off in Stadium GS.) Two hits and Rage is at a useable level; any more and pain will be dished out to the unfortunate.
Rage can be used by any RBY Pokémon (except Electrode and the 'no-TM club') and also by a few GSC Pokémon, so you shouldn't have much trouble finding a pissed off, high-endurance beast who will fit your team. It needs testing and it sounds absolutely crazy, but I think it has potential. Heh heh.