By Boosting Alfred, meaning Aichi uses Alfred's own effect for the boost.
Passive【V】 : During your turn, for each
《Royal Paladin》 Rear Guard you have, this Unit
gains +2000 Power.
Calling Gancelot to the Rearguard Circle behind Alfred for that effect.
U can call any grade to any of the Rearguard Circle on field, there's no restriction. Reason why you want to call grade 3s to the Front Row because it usually has high attack points, and it has not special effect when its on the Back Row.
Grade 0 -> Able to boost the unit infront of it when it is in the Back Row.
Grade 1 -> Able to boost the unit infront of it when it is in the Back Row.
Grade 2 -> Able to intercept for any units being attacked by an opponent when it is in the Front Row. (Except for itself)
Grade 3 -> Able to perform Twin Drive Check when it is a Vanguard.