Unicorns and Pegasi
Stallions can breed every year.
Mares can foal for 50 years (50-100 foals total within that time span depending on how many sets of twins) then skip 50 years before they can breed again.
Mares can foal for 50 years (50-100 foals total within that time span depending on how many sets of twins) then skip 50 years before they can breed again.