Blissey. I bred a 31/*/30/*/30/* Impish Natural Cure one on my LeafGreen cart, then tutored Mimic onto it, and then gave it it's moveset via the Mimic glitch on my Soul Silver cart. Legit parents, legit breed, legit moveset, but not an actual PCNY Event "Wish" Bliss (even though it has Wish).
The rest of my team was 100% legit though.
The rest of my team was 100% legit though.