It seems that gladius cards are not much being used at higher leagues. I only battle at low tier brawls and mostly encounter gladius cards.
One of the gladius cards I want to have that I don't own yet is Quora Towershield. A lot of players say that she is far better than Kron. 😁
!1UP
Quora is better than Kron, especially with Llama.
At the higher leagues, the normal cards are probably better to use since the higher level Gladius aren't available. Even in the lower leagues, they have to be used well.