For Nolan he uses different pokemon every time so just use a variety For Tucker I suggest a Water/Ice to take out Salamence and Charizard and a grass type for Swampert For Lucy an Electric for Milotic a psychic for Crobat and a ater for Shuckle For Greta I suggest a good flying and fighting For Spenser an electric and a figthing For Brandon a good electric and steel and for Anabel a dark fighting and Water hope that helps
Powerful Blaziken 88's faq has helped me the most.
Starmie, Slaking, Sceptile, Alakazam, Gengar, Medicham, Blaziken, Swampert, Metagross and Salamence are all VERY useful in the Battle Frontier.