How many Defense Team members should have Rally skills?

Right now, I have my three Defense team members. It's a mixed emblem team, using Defense Tactic seal.

I have a Guidance Flier, an Armored Boots Armor unit, and an Infantry unit. I was thinking of having Swap on the Armor unit, with Rally Spd/Res on the Flier and Rally Atk/Def on the Infantry unit. The third member will just be an Arena bonus unit, probably with some sort of Positioning skill.

Seem reasonable enough? My other options are to give the Armor unit a Rally skill and a different unit Swap, or I could give Swap to two of my core units and have a single Rally.