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
certain pokeblocks can make Pokemon happier if your talking about Pokemon emerald or Sapphire, but generally the more you raise your Pokemon the happier they become.
by breeding an evie
sooth bell
Not allowing it to faint in battle
this does not make sense
Noi, you cannot make Pokémon with any of the Unowns in Pokémon Platinum.
Noooooooooooooooooooooooooooooooooooooo!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
There is none. HAHAHAHAHA ^-^
you cant catch it anymore
No!
YOU CANT!!!!!!!!!!!!!!! - - /
There are several options: -Walk around with your Pokemon in your party. The more time you spend walking with them, the happier they get. -Battle with them (but don't make them faint!) -Grooming services. In diamond and pearl (and platinum), there are grooming services at the resort area. In HG/SS, grooming can be found in pallet town (with daisy in the afternoons), and in Golden Rod underground