Pokemon conquest

a ground type pokemon will render Nobunaga's pokemon useless, all you gotta do is wipe out all other pokemon then use your ground type to beat him.

Having pokemon that can knock Nobunaga's allies' pokemon into the damage nodes also helps.

I used Gurdurr and a Gyarados. it worked wonders. Nothing like smacking that Pansage into a fire node and laughing as it bursts into flames and is knocked out.