Q&A for How to Raise Friendship Level in the Pokémon Games

The luxury ball wasn't added to the game, unless you trade from Ruby, Sapphire and Emerald, or hack it in.

Luxury Balls double the rate of happiness gains, whereas Friend Balls start all Pokemon that are caught with it (regardless of the Pokemon's base happiness) with a Base Happiness level of 200.

You need to have an Umbreon. Go to your Father's gym (Norman's), talk to him, buy a Pokeball in the Pokémart near the gym. Sell it on the Pokemart on the Pokémon League, go to the starting town, talk to your mom, release your Umbreon on the computer of the Pokémon Center of the tree city with the flying gym. At the same Pokémon Center Box you released it in, buy a Pokéball and it will be a luxury ball.

You can use plenty of rare candies or grind levels. Trade if necessary because some Pokemon only evolve through trading. Sometimes you need to use an special stone (like the fire stone, the water stone, etc.).