plants vs zombies garden warfare 2

[sirnutsbones]

is it possible to get a legendary character or piece from a phenomonal character pack?

[pandareno1999]

No.

You can get them from the 35K pack, occasionally from Rux or the red community chest.  Once you have all of the "regular" characters, the phenomenal character pack will disappear from your sticker shop.  Be aware that it takes tens of millions of coins spent to collect all of these stickers.  It's a very long grind.