I require some help and tips on three campaigns.

I am having issues fighting blobs of Gothic infantry. In the missions "Catalunanian fields" of Huns and "Loose Ends" of Bari, I have to Gothic infantry that consists of pikemen, huskarls and Huskarls don't fear castles as much, and pikemen counter Cataphracts and Hunnic cavalry. Any ideas on how to clear blobs of onrushing Gothic infantry quick?

In the Vietnamese mission, "Castle Seige", someone advised to use 10 Elite Battle Elephants to clear the Blue Chinese army, however, this means that I have to spend a lot of time booming and tanking the Cyan Chinese attacks until I get enough resources to build them. And, I can't build Rams or Trebuchets to deal with the Chinese Keep Towers. Any ideas on how to destroy the Blue Chinese army?