Slug Buddy in The Way of the Sponge appears to be red in color. In Squid Defense, it is now mainly brown in color and it appears to be bigger in size as well. The words "Slug Buddy" is also written near the top.
The Way of the Sponge
Slug Buddy was first used by SpongeBob when he was training hoping to impress Fuzzy Acorns. Slug Buddy ends up knocking SpongeBob away however.