When I want to get someone up to Lv. 50 fast, I usually:
1. Do the rub/feed/play cycle in Amie until they have 3 hearts.
2. Give it a Lucky Egg, activate Exp. Point Power Lv. 3, and do 2 Rotation Battles at Le Wow.
Usually, that is enough for me. If I need to do any more leveling after that, I go and activate the challenge writ at Battle Chateau and do a few gym leader fights.
Okay, can someone clarify the infamous Bad Egg thing? I'm reading it was a severely overblown incident that had nothing to do with Wonder Trade and was just one person's file/3DS dying.
I need to know for certain.
The way the game handles Pokemon sent over WT, it won't send someone if their data isn't good. Most likely situation is the person's copy was messed up, since there have been little word of bad eggs - only a lot of stories.
If it is real, it's pretty isolated since I haven't heard of anyone getting it, and there have been thousands/millions of trades in the month the games have been out.