Where Is Happiny In Pokemon Platinum?

Go to route 210 and go to hte left side where there's really tall grass where there's a rancher go up with the bicycle,then there will be twins,you'll have to fight with them,then continue walking and you'll see another man talk to him and he will fight with you,you'll see happiny.Trust me I also had this problem.

You can breed one by catching a chansey. Put the chansey in the pokemon daycare and MAKE SURE THE CHANSEY IS HOLDING THE LUCK INCENSE ITEM or else you will just get a chansey egg. If it is holding the luck you will get the happiny egg. If you walk around with the egg for a while it will hatch into a level 1 happiny.

Get it in a trade pokemon diamond or pearl

Trade from diamond because shes on diamond

Pokemon mansion
here you can find
eevee

The thing is, you can't get it unless you do a trade, but you can get  chansey, some hold oval stones, ( mine did) and you just evolve them by level I think. You find them on the route in between celestic. Although they are rare and I just got lucky.

Make a chansey hold a luck incense and breed with ditto

Get a girl chansey and a ditto and put them in the daycare

I don't think you can just catch it in pokemon platinum I think you'll have to trade it from pearl or diamond

Keep talking to Mr. Backlot until he says he saw a cute Happiny. [only if you have national pokedex ]

Its impossible to gat happiny before getting the national dex unless you have another game and ds or a friend willing to trade.
If you have the national dex then you can get a ditto in the trophy garden.
Then, on route 209 or 210 you can get a chansey.
Give the chansey a luck incense and breed the chansey and ditto in the day care center in Solaceon town. The egg should be a happiny

Heart home city south east a hiker gives you a hap-piny egg