Lorelei: Dewgong level 64, Cloyster level 63, Piloswine level 64 (replaced Slowbro), Jynx, and Lapras level 66.
Bruno: Steelix level 63, Steelix level 66, Hitmonchan and Hitmonlee level 65, Machamp level 68 (his 2 Onix have evolved).
Agatha: Gengar level 66, Crobat level 66, Arbok level 68, Misdreavus level 65 (replaced Haunter), Gengar level 70 (her Golbat has evolved).
Lance: Gyarados level 68, Kingdra level 66, Aerodactyl level 70, Dragonite level 66, Dragonite level 72 (one of his Dragonair evolved, and the other was replaced by Kingdra).
Rival: Heracross level 71, Alakazam level 69, Tyranitar level 72, and depending on who you chose at the start;
If you have Bulbasaur: Gyarados level 71, Exeggutor level 73, Charizard level 75.
If you have Squirtle: Gyarados level 73, Arcanine level 71, Venusaur level 75.
If you have Charmander:Exeggutor level 73, Arcanine level 71, Blastoise level 75.