Yeah, I stumbled upon him whilst I was *still* looking for a Bagon. This was back when 10 year old me basically decided this Emerald game was so infinitely better than everything else I had on GBA that I would play it religiously, levelling all my pokémon to level 100 (I did eventually manage to capture every pokémon obtainable without trading and level them up to 100. God I was boring back then), so my pokémon were about high 60s after beating the Elite Four, doing some Battle Frontier and a load of rematches. He still absolutely wiped the floor with me.
Even now, him and Red are the only players I still struggle against even with ample preparation - before I EV trained my Metagross, Swampert and Latios for Battle Frontier I tried challenging him, Swampert soon became last man standing then he sent out Cradily. Post-EVs, Latios nearly one-shotted the entire team. Even then, Metagross vs. Metagross was extraordinarily even and I had to heal.
So back to the original questions: No, but yes. I discovered it on my own, so unlike some posters I already knew about it when reading this. Yes, I have been successful, many times. Also, it's my second favourite battle in the my first two generations (III and IV) after Red.