I finished both 98 and 99 using earth main, suigetsu/kinkaku(for 99),gnw tenten and gnw sakura. And i tell you using sakura is a must if you are 26-30k power.

i think you can probably use these ninjas with any class(havent tried yet but since i got out with almost full life there is a possibility for all class). Anyway put the ninjas in these way.

x-gnw tenten-gnw sakura

x-x-Earth main

x-x-suigetsu/kinkaku

Suigetsu works really well for level 98.

For 99 I used-

kinkaku-gnw tenten-gnw sakura

x-x-x

x-x-earth main.(any main)

Hope it helps. (-^_^-)