Moloko

Moloko, known as Marumoko (マルモコ) in Japan, is a sheep virus from Mega Man Battle Network 4. It rushes from the right side of the field to the left across the row that it's on very quickly. It is protected by its wool, and the only way to damage it is to shear the wool. However, after it rushes across the row and reappears back on its side of the field, the wool fully reappears. The Slasher battle chip is very effective in taking this virus out.

Moloko
Moloko is a pink variant with purple ears and peach skin.

MolokoEX
MolokoEX is a yellow variant with dark gray ears and black skin. Milko in Phantom of Network.

Milko
Milko is a light blue variant with brown ears and peach skin.

MilkoEX
MilkoEX is a brown variant with tan ears and peach skin.

Macko
Macko is a navy blue variant with green ears and peach skin.

MackoEX/MolokoΩ
MackoEX is a black variant with dark blue ears and gray skin.

Battle Chips
Moko Rush (モコラッシュ) is the Battle Chip family from Moloko viruses.

Trivia

 * The Moloko's original Japanese name, Marumoko, combines "maru," the Japanese word for "round," and "mokomoko," the Japanese word used to describe something fluffy. Strangely, V2 version of this virus named Milko, which bears resemblance to "milk", when "moloko" is the Russian for "milk".
 * Sheep Man from Mega Man 10 bears a resemblence to Moloko. Coincidentally, his stage in Mega Man 10 also appears to be set in a Cyberworld-like enviroment.