Answer 1

Well, there are many ways to raise a pokemon's happiness(friendship)
Here is a small chart for the different things that can increase
your Pokemon's Happiness.

| Event               |Normal | Soothe Bell | Luxury Ball | Both
|---------------------|-------|-------------|-------------|-------
| Walked 256 steps    | +1    | +2          | +2          | +3
| Use Healing Items   | +1    | +2          | +2          | +3
| Using a Stat Item   | +2    | +3          | +6          | +7
| Go up a level       | +2    | +3          | +6          | +7
| Happiness Berries   | +2    | +3          | +3          | +4
| Veilstone Massage   | +3    | +4          | +5          | +6
| Resort Area Massage | +5    | +6          | +6          | +7

You can find soothe bells at the pokemon mansion. Here is a list of berries that increase Happiness:

| Berry        | EV Points it Lowers
|--------------|-------------------------
| Pomeg Berry  | 10 HP EVs
| Kelpsy Berry | 10 Attack EVs
| Qualot Berry | 10 Defense EVs
| Hondew Berry | 10 Special Attack EVs
| Grepa Berry  | 10 Special Defense EVs
| Tamato Berry | 10 Speed EVs

Stat items are your EV items, such as Proteins, HP Ups, PP Ups, and so on.
I am not sure if Rare Candy falls under level up happiness, Stat increasing, happiness, or both.

Comments

when you say "both", do you mean.....
1. luxury ball and soothe bell
2. luxury ball and normal
3. soothe bell and normal

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It means Soothe Bell and Luxury Ball. Basically for each of those you get an extra +1 on top of the normal value.

Answer 2

well massages in veilstone city, ribbon syndicate spa treatment, battle but not being knocked out, soothe bell, poffins that are the flavor that they like, those things and i should know i have raised almost every pokemon

Answer 3

put your pokemon in the first party and give it a happiness item like soothe bell. it's works to my budew! hope this usefull...