Pegasus is the name of a specific winged horse, it is not what winged horses are called.
Shows what you know about D&D.
The plural is "Pegasi"
Training one to carry a person takes 6 weeks and a DC25 handle animal check. And the rider must pass a diplomacy check to see if the pegasus likes him/her.
COMBAT
Hit Dice: 4d10+12 (34 hp)
Attack: Hoof +7 melee (1d6+4)
Full attack: 2 Hooves +7 melee (1d6+4) and Bite +2 melee (1d3+2)
Flyby Attack is one of its feats.
They use sharp hooves and a powerful bite. Mated pairs or herds fight as a team, and will fight to the death to defend their eggs, which are worth 2,000 gold pieces each.
Now the Unicorn:
Hit dice: 4d10+20 (42 hp)
Attack: Horn +11 melee (1d8+8)
Full attack: Horn +11 melee (1d8+8) and 2 hooves +3 melee (1d4+2)
EDITED Actually they look fairly closely matched, not sure how the flyby feat would effect the fight tho. (didnt read that part
)