How has nobody mentioned the Elite Four from the original Pokemon? Back before we all knew how to create a super-death team. Back before we knew every move and skill our opponents knew. Back when Pokemon was new, and you had your beloved party ready to take you to the top....well, welcome to hell, kid! You thought a gym battle was rough?! Try five in a row!
First up was Lorelei, who combined Ice and Water type pokemon with some psychics as well...I'd never even seen an Ice-type pokemon before Lorelei, let alone 5! Next up comes Bruno, also known as Brock on steroids! Two Onix and three nasty fighting types to get past here. Next up is Agatha, with the seemingly-invulnerable Ghost-type pokemon. Her Gengar and Haunters are mean little buggers, plus the rest of her team confuses and poisons with ease. The leader of the Elite Four, Lance, strikes out with the un-encountered dragon pokemon! Hyper Beam can rip your team a new one, and all of his five dragons are rough. Finally, your rival steps up, apparently sick of getting beaten (and still upset that I named him Ballz in the beginning). His party of six pokemon are a rough match-up, especially with yours beaten and bloodied from the past four fights...in a row!
All of this is just so you can earn the right to fight the strongest pokemon ever made (No, Arceus did not exist at this time).