pokemon rating

Ho-oh
Nature:Impish
Ability:Pressure
move set:
Sacred fire
Sky attack
Sunny day
Fly

No item

Don't have both Sky attack and Fly. Nature (+Def, -Sp. Atk). So this is a physical sweeper. Also, the only type that a flying type move covers that fire doesn't is fighting, and most wouldn't use a fighting type, so I wouldn't recommend having either, but Sky Attack is a very powerful move so that is up to you. I would give him Earthquake to cover his rock weakness. Also this particular Ho-oh will have high defenses so I recommend giving him recover. It will really annoy your opponent. The move set I would give it is (you do not need to use this moveset):

Sacred Fire
Recover
Earthquake
Sunny Day/Sky Attack (up to your preference)

For an item, many things will work, I think Life Orb is a very safe bet, but Leftovers works just as well. If you really want the extra power Choice Band is for you, but that is all based on what you want.

i don't agree with sunny day and you mustn't have 2 flying moves on it, better learn it thunderbolt or recover.

i'll stick with sunny day to power up sacred fire.