Traded Pokemon always gain levels faster than Pokemon you catch yourself.
If the Pokemon you're trying to level up is considerably weaker than your other Pokemon and can't defeat the wild Pokemon in the area, put it in front and switch it out immeadiately with one of your better Pokemon. This works better the wider the gap between the Pokemon you're battling and the Pokemon you're trying to level up.
Alternately, you could use the action replay cheat for super fast experience.
without hacking, 100 with hacking, 999 and then reset to 0 and no more exp gain.
As Pokemon battle, they gain experience. With enought experience, they will gain levels, which helps them learn moves.
Fight strong opponents and have your Pokemon hold lucky egg.
you have to go to hearthome and gain dialga or palkia
your Pokemon aren't supposed to gain exp points in the battle arena
an exp.share is an item when you give it to a Pokemon witch isant the first in your party and it will gain exp.point attomattacly!
i believe that you are thinking of something else because i have never heard of a "mega exp gain"
Eat Joy Seeds to gain 1 level, or Golden Seeds to gain 5 levels.
Press A at a large, grey boulder to gain the power to push it.
Its a item that you give to a Pokemon and it gives the Pokemon that you gave the exp share to exp points to help a Pokemon gain levels
Gain max friendship, and raise eevee one level at night.
EARNING diamond MASTERY LEVELS WILL GAIN YOU FREE BROWNIE POINTS