you can get 16 key items in Pokemon platinum.
Over 9000! Im just kidding. There are many im thinking at least more than 200 including event items
To thaw out your Pokemon with no items use an attack just before you get frozen
You download stuff for your pokemon games. It could items or actual pokemon.
Happiness is gained by taking care of your pokemon giving it items, training it and many more things. Once it's happiness reaches the max happiness have it level up to evolve the pokemon.
some items are used during pokemon trading.
You can't. The only way to trade items is to make a Pokemon hold the item you want to trade.
There is no limit
I think 5
no but you can trade Pokemon holding the items.
The max number of most items and healing items is 999 for D/P/Plat.
To thaw out your Pokemon with no items use an attack just before you get frozen
go to your PC then go to move items then get the items from your Pokemon
POKEMON
you are unable to send any items from the past games to pokemon black/ white
Yes
Only if there attached to Pokemon
you die
You need to have a Pokemon hold the item then trade the Pokemon.