For newer players [turn the sound on]
After ff4 block, this is how to counter Yoshi's options:
b: 10~12i punish h/m
db: 12~15i punish m
12i mid OS both
spin: homing [regular throw = BT throw]
spin: dash in> wait> launch
Punishers not to do: duckjab: whiffs at tip range
His hopkick is the only move he has that I hate the most because it can crush mids, like his Flash is not enough.
Oh, and his ff4, that knee natural launcher safe on block he has, because he definitely needs it.