How do you get Pokemon to love you when they're traded?

Answer 1

Keep letting them win battles, contests and give them items like Protein and Hp Ups.

Also, the Soothe bell works well too. It's possibly different to where the Soothe bell location is in Sapphire and Emerald, so you may have to search Gamefaqs for that. But in Emerald, the lady in Verdanturf, if she sees a Pokemon that likes you a lot, she'll give you the soothe bell.

But all the while, said information above is helpful. The Lady in Verdanturf, next to Wanda's house will examine your Pokemon and you can check to see if your Pokemon likes you too.

If she says "It adores you. It can't possibly love you anymore. I feel happy seeing it." then you know they really love you~

Answer 2

Really, you just need to walk around with them and have them win fights. I've heard there is a point system similar to the egg hatching method, but I can't be sure.

Low level (Egg) Method

In Silver, Gold, and Crystal, go to Ecruteak City and walk all the way to Olivine City. Repeat this process a near countless number of times (seriously, this takes a long, long time to do this way), and level up the Pokemon. (I'm assuming you want to increase the friendship level for evolution) If the Pokemon evolves due to friendship levels, it should evolve.

In Diamond, Pearl, and Platinum, go to Solaceon Town, it's pretty much the same procedure. Go North, all the way up to where the Psyduck should be/have been and then walk all the way down to the southern part of route 209 without going west. Return all the way up to the Psyduck spot and repeat. A soothe bell wouldn't hurt either.

The theory behind this is that As you cross a boundary between routs/towns, there is a bonus step to the step counter on friendship. Likewise, there is a negative bonus when you ride a bike, but the route change bonus makes up for that and then some. It is nicknamed the Egg Method because the same rule applies for eggs.

Stat Plus ("Superman's Medicine Cabinet") Method

***This is an insanely expensive method that I would not recommend unless you had the cash to spare and then some.***

Go to the department store, and buy as many different Stat increase items as you can (Protein, Calcium, etc...). Keep giving these items to your traded Pokemon, and keep track as to how many you have given. At some point, the Pokemon will reject the Stat increase item, so move on to the next. Repeat this process until it has consumed at least 40 materials (some happen at 35, and some happen at 45. it depends on the Pokemon, but 40 is the most common). Level up the Pokemon, and the friendship level should be maxed, and if possible, it will evolve, not only that, all other Pokemon of the same species and level will be weaker than your traded Pokemon

This will cost and absolute minimum of 343,000 Pokedollars unless you either cheat, or find some underground or laying around or something. Even I wouldn't do this unless the Pokemon was giving me a hard time. The nickname was, an inside joke, and secondly, Not my name for it. The joke was how much Advil Superman would need if he had a headache. This method is legit though.

Arena (Battle Brick) Method

Go to the battle tower, in any game available, and equipt your traded Pokemon with a hold item to increase happiness, in any game available, and continue to fight and win with this Pokemon. By switching this Pokemon into battle, they receive a bonus to their Happiness, and for winning, they receive another bonus. If done correctly, the Happiness will go up, but Experience will remain the same.

This method is named the Battle brick because all one does is Fight in Battle tower, and does not gain any experience. Like a brick on a chain, It can't help but follow you but it doesn't learn anything when whipped at another Pokemon.