Does Lucky Egg boost the experience gain from Exp. Share?
Solution 1:
If you equip a Lucky Egg to a Pokemon, the gained experience from EXP Share will be affected by the egg.
For an example, if a normally the participating get 100 exp and the non-participating Pokemon will get nothing, without EXP share...
In Gen 6, with EXP Share on, instead of splitting[1] the exp amongst everyone, the participating Pokemon would get 100 exp (with no Lucky Egg, the yield 100% of the total exp gained for each participating), while another non-participating Pokemon (with no Lucky Egg, the yield 50% of the total exp gained for each non-participating Pokemon).
Giving the participating Pokemon a Lucky Egg (adds 50% exp), will yield them 150% or 150 exp [100 + (100*.5)], and giving the non-participating a Lucky Egg they will get 75%, or 75 exp [50 + (50*.5)].
A = Participant
B = Non-participant
C = Non-participant
+ = Lucky Egg
No EXP share, no Lucky Eggs:
A = 100%
B = 0%
C = 0%
With EXP Share, no Lucky Eggs:
A = 100%
B = 50%
C = 50%
With EXP Share, two Lucky Eggs (x1.5):
A+ = 150% (x1.5)
B = 50% (x1)
C+ = 75% (x1.5)
1 The item Exp. Share will revert to Exp. All as in Generation I, where when one Pokémon holding this item participates in battle, all other Pokémon in the team receive experience as well. Unlike in Generation I, the experience is not split but rather received by all Pokémon. This means that the participating Pokemon receive 100% experience, while non-participating Pokémon receive 50% experience. Source.
Solution 2:
Actually it does not in Pokemon x/y. I've tested this using spreadsheets. I used my own delphox and flareon to test this. When using the lucky egg on delphox, and not sending flareon out, flareon got exactly 50% of the enemy pokemons base exp, not boosted.
Delphox started out with 3701 needed for next level, gained 1170 boosted from a battle. Flareon (who did not participate) started out with 2181 needed and ended up only gaining 390.
If you take the 780 gained and divide it by the 1170, you get 66.66666666666% increase which is what the lucky egg gives you.
I understand this is an old post, but this will give some people who are googling for the answer a better understanding.