In the Pokèmon Mansion, (South of Hearthome City) in one of the rooms on the left, there is a maid who gives you a Soothe Bell.
Give a Soothe Bell it raises happiness.
if your Pokemon level ups, its happiness will increase automatically. but if you give your Pokemon a soothe bell, its happiness will increase faster, and it will evolve faster (by certain Pokemon). also return will do more damage
You can find a Shell Bell at Hearthome City in Pokemon Platinum.
Let your Pokémon hold Soothe Bell and train OR feed it Berries that lower its stats but makes it friendly- DON'T overdo it.
None, the soothe bell is only used to increase happiness of your Pokemon you don't need it to evolve a Pokemon that evolves from happiness though it is a good idea to use it if you have it.
by training it as your main pokemon and giving it the soothe bell
to get it hornny to up its happiness
250 happiness-400 happiness depending on lvl
Makes your pokemon's happiness go up faster.
You give on of your Pokemon the soothe bell and it will get happy faster.(It helped me evolve my eevee and togepi.)
You can find it at Hearthome City.
It is a pokemon-held item that makes the pokemon gain twice the happiness points.