From the Super Mario Wiki
The three size variations of Protobatter.
A Protobatter is a round creature that holds a club and resembles a Flurry. It is found inside the Pump Works of Bowser's body in Mario & Luigi: Bowser's Inside Story. It grows up to two to three times larger whenever Mario and Luigi attack it. It also makes shockwaves with its club like Clumphs from Superstar Saga and attacks by spitting a piece of batter and slamming it with its club at the bros. The direction it holds its club is to indicate which one of the Bros. is being attacked. This attack can be countered with the hammer. It may miss the swing up to two times in an attempt to lower the player's guard. Protobatters also have stronger cousins called Pwallops that appear in the Energy Hold.
Names in other languages
|From 蛋白 Tanpaku, an abbreviation for protein. It is a pun on the Japanese honorific くん -Kun, typically used for young boys.
||From the verb Batear (To bat) and the suffix -zoide.
||Pun of the protein Albúmina (Albumin)
||Pun on Protein and Protz (swank)
||From "proteina" (protein) and "portentoso" (powerful)