You cannot get Beldum with Ruby inserted in Pokémon Platinum in order for Beldum to appear in the wild, check in with Dawn's sister in Sandgem Town. She'll tell you what Pokémon is currently swarming. Beldum is 1 of the many swarms so it'll be one of them before you know it because it changes daily.
I don't think you need ruby at all. All you need is national dex andtalk to the little girl in sandgem town. Eventually she will say that there are lots of beldum in the desert between stark mountain and the peaceful place (i think its the relax area?) You should catch one on about lv 52
you get it after you complete the national dex route 203 with Pokemon ruby inserted in ds
Train it to level 20
You CANT. MWAHAHAHAHAHA. -coughs-
Level 33.
The Pokémon that are inserted into Pokémon Platinum based on the Pokémon Gameboy Advanced Game Pak that's inserted are as follows: Gengar is inserted into Pokémon Platinum with any of the 5 Gameboy Advanced games inserted. Seedot, Nuzleaf, Mawile, Zangoose and Solrock are inserted into Pokémon Platinum while Pokémon Ruby is inserted in the DS' bottom slot. Lotad, Lombre, Sableye, Seviper and Lunatone are inserted into Pokémon Platinum while Pokémon Sapphire is inserted into the GBA slot. Caterpie, Metapod, Ekans, Arbok and Growlithe are inserted into Pokémon Platinum while Pokémon FireRed is inserted into the DS' GBA slot. Weedle, Kakuna, Sandshrew, Sandslash and Vulpix are inserted into Platinum while LeafGreen is inserted into the GBA slot. Pineco, Shuckle, Teddiursa and Ursaring are inserted into Platinum while Emerald is inserted into the GBA slot on the DS.
go to sandgem town, in dawns house a girl there will tell you routes where rare Pokemon can be found, hopefuly she will say a route where beldum can be found
yes,if you had or knew someone who had a Pokemon ruby/sappire/emerald who could trade you a beldum.
I am sorry to say this but, you cant catch any of the Pokemon in platinum in ruby unless it is a hoenn Pokemon.
Probably but it would take a lot of time
You could get one, but you'll need to trade it over from Pokemon Sapphire, Ruby, or Emerald.
you must have Pokemon ruby inserted.