The boost to some of Magics weaker creatures opens up all manner of intriguing possibilities, including making creature tokens nigh unblockable, doubling up on Disguised creatures Ward protection, and more
According to Magic Librarirites, For Avacyn Restored prerelease, WOTC sent out approximately 6,000 Helvaults globally for this exciting and unique Prerelease event 'of the roughly 6,000 Helvaults we [Wizard of the Coast] sent out, we selected 30 Helvaults to get this special treatment
If your library contains fewer than X cards, you'll put them all into your hand
However, in the white back stamped Pikachu I own I see no evidence of this whatsoever
Multiple creatures may attack at the same time but the turn player may declare their list of attackers only once
Pokmon 151 is still early in its release, and we havent had any major events featuring this set outside of Japan, but I have faith that both archetypes below will see success globally soon enough