i believe that you are thinking of something else because i have never heard of a "mega exp gain"
My Action replay cam with exp codes, look there because its in a folder. But anyway mega exp gain 94000130 000002ff 62106fc0 00000000 B2106fc0 00000000 100458dc 0000ffff D2000000 00000000 Wild Pokemon will give you 65535 EXP. Trainer's Pokemon will give you 98302 EXP. I got this off the internet from someone else.
mega exp gain 94000130 000002ff 62106fc0 00000000 B2106fc0 00000000 100458dc 0000ffff D2000000 00000000 You have to switch out from one pokemon 2 another 2 have both of them share the exp. because one pokemon cannot manage so much exp n thus if u use one pokemon it will fail. 2 or more pokemon can be switched to share exp. N hold "R" at the end of battle.
without hacking, 100 with hacking, 999 and then reset to 0 and no more exp gain.
This code will give you 65565 exp. for wild pokemon, and 99999 for trainer pokemon: 94000130 000002FF 62106FC0 00000000 B2106FC0 00000000 100458DC 0000FFFF D2000000 00000000
you gain boosted exp. points from Pokemon you get in trade
94000130 feff0000 621bfb0c 00000000 b21bfb0c 00000000 1000229c 0000270f d2000000 00000000
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
hbvfjhbdfjhbhbfdvjb vv n,v nf hbgmvhbvfhfnjbjkbfksbjbnvgjgvgcdgvfkgvvhgvhubvfshbv hbhvhvhbvhbvhbvhbbhbvbvjnbcvkvjhdvfghbhgkhkuubhbgrbghuhbguhbgfu POOP!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
yes it can evolve
Unfortunatley it is like emerald no you will not gain exp by battling in the battle frontier however you can get rare items and berries
give it to the weakest pokemon on your team and the pokemon you gave it to will gain exp with out battling simple:)
In Pokemon Diamond, Professor Rowan's assistant will give the play an Exp Share item on Route 206. One may also be won in the Pokemon Lottery on Jubilife TV.