Lorelai wasn't so bad. Granted her Ice Attacks were lethal if you were unfortunate enough to be facing her with say a Flying type but a simple Thunderbolt usually KO'd her without much thought(exception being Jynx where Flamethrower is necessary). Bruno, frankly, was a cakewalk. Considering how dominant Psychic types are in Generation 1 made his Fighting Pokemon irrelevant(Even Flying Types kick his ass). Then his Rock Pokemon could be taken down any number of ways(Fighting, Ground, Grass or Water). Lance was pretty much Thunderbolt the Gyrados and Ice Beam/Blizzard/Ice Punch to Victory because Ice was the only type super effective against Dragons(Only 1 Dragon type move and it did fixed amount of damage so the thought of Dragon on Dragon just simply didn't apply).
Of all the Elite 4 Trainers, I found Agatha to be the most annoying if you didn't have a Psychic type or Ground Type that was able to KO her in one move. Minimize, Substitution and other moves made knocking her Pokemon out in 1-go extremely difficult if your Pokemon were too slow or missed during the early part of the battle. That gave her the opportunity to pretty much laugh at you as you as her Pokemon evaded every attack you launched at her while she used Hypnosis and Dream Eater(a combo she uses in the anime) to knock you out.
Overall though, the Elite 4 isn't really that much of a challenge. You just need Pokemon with the right type advantage and with moves that don't miss often.
