Where to train for the 2nd E4 after beating the Kanto gyms?

[Steven]

I've beat the Johto and Kanto gyms and am curious as to where i should train for the 2nd round of the elite four and im rolling with:

Arcanine-54
Porygon-Z-56
Feraligatr-55
Tyranitar-56
Metagross-55
Lucario-55

 

[Annie]

call the gym leaders and battle them over and over again

 

[Annie]

call the gym leaders and battle them over and over again

 

[Pedro]

Battle Red

 

[Annie]

call the gym leaders and battle them over and over again