You can't catch Ho-Oh in Pokémon Platinum, you need to trade it from Pokémon Colosseum or with someone who has it.
you can't get ho-oh in Pokemon platinum only by cheating with AR or r4 or migrate it of Pokemon gold
there is no ho oh or lugia event in Pokemon platinum
you cant unless you have a game boy game that you catch it on and then migrate it to platinum
You can't get it without hacking or from an event
It is an event only Pokemon.
You cannot find Ho-Oh in Pokémon Platinum because he is not available in it, so you need to migrate it from the gameboy games.
you can only get it in Pokemon gold
You can't get a Ho-Oh in Pokemon Platinum only Heart Gold and Soul Silver, unless you migrate.
You can't without a event or action replay or a friend with Ho-Oh.
No unles you use A.R.
You haVE TO CHEAT OR trade or event.
Not unless you have a cheat code.