You can't without a event or action replay or a friend with Ho-Oh.
you cant unless you have a game boy game that you catch it on and then migrate it to platinum
You haVE TO CHEAT OR trade or event.
To obtain Ho-oh on Pokemon Platinum you must use an Action Replay(AR) OR trade it from an earlier game OR wait until Pokemon HeartGold (and Soulsilver) comes out next year, which is a Nintendo DS remake on the original Gold and Silver Pokemon games.
You can't find a Ho-ho in Pokemon Diamond. You have to migrate.
you cant get him in platinum
you can't get ho-oh in Pokemon platinum only by cheating with AR or r4 or migrate it of Pokemon gold
You can't catch Ho-Oh in Pokémon Platinum, you need to trade it from Pokémon Colosseum or with someone who has it.
there is no ho oh or lugia event in Pokemon platinum
You can't get it without hacking or from an event
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.
Ho-oh can be caught on Navel Rock in R/S/E. It can then be traded to D/P.
You can't get a Ho-Oh in Pokemon Platinum only Heart Gold and Soul Silver, unless you migrate.
you cant unless you have a game boy game that you catch it on and then migrate it to platinum
you can only get it in Pokemon gold
It is an event only Pokemon.
there is no Pokemon called ho ho ho but there is one called ho ho who is in Pokemon crystal/gold
trade from Pokemon platinum via wifi, you'll need the persons friend code though