To level up a Pokemon quickly, go to Victory Road. In slot one of your party, put a strong Pokemon (level 55+ minimum). In any other slot, put the Pokemon you want to level up, holding the Exp. Share. Battle the wild Pokemon and trainers in Victory Road to level up your Pokemon.
NOTE: Do NOT use Rare Candies. Although th elevel up your Pokemon, they do not raise the attack, sp. attack, defence, etc. of that Pokemon. Also, do NOT leave your Pokemon at the daycare center. They will delete a random move when your Pokemon is trying to learn a new one. The Pokemon's happiness will drop, making it harder to evolve some Pokemon if maxed happiness is needed for evolution (such as Golbat --> Crobat)
There is an easy way to get your Pokemon to a certain level. All you need to do is collect rare candy and use it on the Pokemon you want to level. This will automatically level up your Pokemon.
keep battling Pokemon and people
Give them rare candies which increase a pokemons level by one.
well u could train alot or
Easy play well
Easy way to do this is to give it the item exp share then use your stronger Pokemon to defeat trainers your wingull soon will level up and evolve.
there is no easy way to get to level 100 just stock up on joy seeds until you have enough for all your pokemon or just the pokemon you want to be at level 100.
the best way to level up your Pokemon in ruby would be battling the elite 4
Battle the Elete Four over and over again and eventually your Pokémon will get to lv. 100.
well just level it up, that's basically it
The fastest way I know is Exp. share. A really easy way is to put your highest level Pokemon in front and give the Exp. share to a weak Pokemon (Level 1-25). Go to Victory Road (fly to Indigo Plateau) and defeat as many Pokemon as possible. Another way for higher-leveled Pokemon is to defeat as many people as possible using the Vs. seeker. You put it in front and find an area with Pokemon around the same level (or weaker). That should work.