How do I use PKHeX to add Events to B2W2?

[Macaulyn]

I tried Mystery Gift Editor, but apparently it only works with BW, and even then I don't know how to use it in those games. Since Black 2 is my favourite in Gen 5, I wanted to add the most important events (specially Legendary Pokémon), but I'd like to know how to do it with PKHeX, and which are the main events for these games.

[BlackShark]

Check this tutorial

In my opinion the most important events distributed to B2W2 in the EU/US were SPR2013 Meloetta, Plasma Gemesect and WIN2013 Keldeo.