Since I apparently have to explain what's the trait_connection tag for in case people have no idea why

The 4 characters in question have cat themes or are related to cats or other types of animals in that line

Yoruichi has the ability to turn into a cat

Grimmjow was a panther like Hollow before becoming an Arrancar

Franceska has lion characteristics on her body. Implying she was a Lion Hollow before becoming an Arrancar

And Ggio Vega literally has a Sabertooth tiger skull on his head. Implying he also used to be a sabertooth tiger Hollow before becoming an Arrancar