um you cant give happiness you have to make the Pokemon happy by doing any of these things:
battle with it
walk with it as the first to battle with
give it poffins it likes
or many others
in my opinion its not worth doing those things if you can just catch the evolved version in the wild, but if you cant good luck
you can't
You can give them a revive that will give the Pokemon half of the hp it has back.
your starter Pokemon if you can
give your Pokemon poffinz
in Pokemon pearl scyther evolves when you give it a metal coat and then it evolves about level 25
give it a pearl .
you have to give it loads of love
Manaphy and Darkrai.
if he has played a Pokemon game before and beat it, give him platinum. Platinum is much harder then diamond or pearl. If he can't choose, ask him if he likes attack or defense. If he says attack, give him diamond. Diamond's legendary is offensive. Pearl's is very defensive. So if he says defense, give him pearl.
you can't you have to migrate them after you got the national dex.
give it poffins
talk to lots of people and they give you eggs