You should use it on the most friendlyest Pokemon or use it on the best Pokemon you have, but remember it works effectivly on the friendly Pokemon.
there is no such thing as a friendly berry in Pokemon sapphire
it takes ten steps for a pokemon to be friendly to you
Of course you can know how friendly you are with your Pokemon!!Go to a Pokemon Center, put all, or maybe 5 of your Pokemon, in the PC. Then check all the the Pokemon you put, depending on their nature, you can see how friendly your Pokemon are. Or you can check your Poketch ( considering you having the PokeFame APP) and you can see how much your set of Pokemon love you!!!
You can either give it pp ups, rare candies, level it up, or give it the soothe bell but the rare candies work best.
to spice up a Pokemon game chalenge your friend but don't make it a friendly me and my friend usually wager our best Pokemon and if he wins challenge him for it but you will have to put up a strong Pokemon aswell
luxuray ball
There are no such things as Best Pokemon. There are tiers, but it depends on personal preference and the ways you train your Pokemon. Of course, there's limits on how far you can train them, like Caterpie, Magikarp, Weedle, etc.
Let your Pokémon hold Soothe Bell and train OR feed it Berries that lower its stats but makes it friendly- DON'T overdo it.
The more you train your poke'mon, the more friendly they will become with you.
Luxury balls make it much easier to make a Pokemon friendly with you. Making a Pokemon friendly causes certain types to evolve and increases the power of the move return
prof.Oak who is in south west of eterna city says some Pokemon evolve by becoming friendly with their trainer.