Puff Ball

Puff Ball, known as Basilico (バジリコ) in Japan, is a virus from the Mega Man Battle Network series that resembles a puffy tree. The virus's mask protects them from all frontal attacks. While attacking, it will stick out its mask and release poison clouds onto panels surrounding the mask. It can only be damage while attacking, with its mask sticking out (the mask still acts as a one panel shield). PuffBall can also use Area Grab to move forward even more. Stronger variants can use Area Grab more times.

They will also avoid walking onto Lava panels; not only will the lava ignore their guard and damage them regardless, but if their whole side of the field is turned into lava, they will refuse to move, merely opening their mask on the panel they're standing on.

PuffBall
PuffBall is a green puff with black and orange mask.

PoofBall
PoofBall is an orange puff with red and purple mask.

GoofBall
GoofBall is a purple puff with green and red mask.

PuffBallΩ
PuffBallΩ is a light-blue puff with black and green mask.

Battle Chips
Poison Mask (ポイズンマスク) and Poison Face (ポイズンフェイス) are the Battle Chips from the Puff Ball family. Both create a mask in front of the user that acts as a shield and releases poisonous smoke. Poison Mask poisons the panel in front of it, while Poison Face spreads poison to adjacent panels.

Trivia

 * Puff Ball was nicknamed お面くん (roughly "Face-kun") during development.