From Gen 1 to 4, all fully evolved Dragon types (that weren't legendaries) were 4x weak to Ice, except Kingdra. So even if the Fairy type existed, any Pokémon with decent Special Attack (and either high speed or decent bulk to take one or two hits) that could learn the Ice Beam TM is still a better option in those games anyway. Basically just don't go into the E4 without one or two of your Pokémon knowing a good Ice type move in those games and you should be fine.
Fairy type just added another option to compensate that newer games introduced more Dragons that can't be just one-shot so easily with Ice. But I don't think it would have made a huge difference in pre-gen 6 games except for Hydreigon. In my Omega Ruby playthrough, I had a Mega Mawile for the Dark and Dragon E4s, and I didn't even use it against Drake because Dusknoir with Trick Room+Ice Punch, Masquerain with Ice Beam, and Donphan just wrecked him.