Getsuga Tensho is his main technique, just like Kamehame for Goku, or Rasengan for Naruto. There is no doubt that he will use it in upcoming fights. He used Getsuga Tensho even with just his Fullbring power, so i will not be surprised if we see Quincy Getsuga Tensho or something like that.
I'm really curious what power his zanpakuto have. And i don't have a clue about it.
Maybe he will be able to use Final Getsuga Tensho, without side effects just like Qunicies use Vollstandig instead of Letzt Stil.