I wasn't very impressed with the Elite Four, once you know the type of each you can breeze through them easily, especially since at that level battles become one hit fests.
Your more or less right, but to find out each type you had to face each trainer, only to find out the next one and then plan for that guy, a long battle in which you formulated your party and strategy trainer by trainer.
Trial and error is not good level design. The 'pattern' for the elite four wasn't that usefull because
a) You had to defeat two of the four of them before you had enough to work it out, which would mean three retries to balance the perfect team, as opposed to four (five if you count Gary who doesn't fit with the pattern). It's not that much of deal.
b) By that point if you didn't have a balance team of pokemon that could deal decent damage to at least 80% of the types in the game you must have been doing something seriously wrong. Given the spread of Pokemon you could meet fighting trainers you where actively encouraged to carry a wide variety of elemental types.
I plowed my way through the Elite Four first try with my balanced team setup.
Now the Elite four in pokemon stadium, with the wacky TM/HM setups. THOSE where a challenge. Still wouldn't say 'zomg best level ever' about it though.
It could have been more balanced though. However don't count out the games between the original and remake,they balanced it in those.
I don't count the games in between because they added too much fluff, Red and Blue where steam lined; Every single GBA/DS game I've played since then I usually gave up part of the way through because it felt too complex for me to ever get the most out of my team. With Leaf/Fire they went back to the original setup, but with Dark/Steel that fixed the psychic imba without flooding a bunch of new pokemon and added some of the useful functions like the ability to re-battle trainers.