i don't think anyone here disagrees that GSC is easy. i do think you can make it more interesting by going straight from gym to gym and mostly avoiding trainers and wild encounters, so you'll have a fairly underleveled team by the time you get to the E4.
on the most recent playthrough, i got the red gyarados right after beating Morty. throw surf on him and he can 2HKO steelix without any leveling up. he's useful, though not stellar, against the E4. basically, unless you're getting lapras, i don't think it's worth raising another water-type in crystal if your goal is to beat the game as quickly as possible.