Remy is a black rat, these rodents can reach a length of 13 to 18 inches with a mass of up to 12 ounces. Film Stuart Little (not book Stuart Little) is a mouse. From this screenshot we see that Stuart is the size of a common toothbrush. Toothbrushes are about 7 inches long. The most common species of mouse that can be white and grows up to seven inches is Mus musculus, the common house mouse. These mice can only grow to be 7 inches long and only weigh a puny 1.6 ounces. Remy is twice as large as Stuart Little and weighs almost 6 times as much as Stuart Little. In a battle of sheer strength, Remy would wipe the floor with Stuart Little.
Strength is not only about strength but smarts and tactics. Once again, Remy wins. Stuart Little is but a child. While bright for a kid, he's by no means a genius and his brain is underdeveloped. Remy is a hyper intelligent adult rat with an intensive knowledge on the culinary arts. No war was ever won on an empty stomach. Remy has a special ability to control humans by manipulating the hair on their heads. Effectively Remy has a giant mech that can squash Stuart Little with its feet. Stuart Little is a decent sailor but he lacks the know-how to command a vessel larger than a model rc boat.
Allies are important for any battle, however, Remy once-again has Stuart Little beat. Stuart Little's allies include his adoptive mother, father, his older brother, and a cat (who often is his enemy). Remy has the support of his father, his brother, hundreds of Parisian rats, a fully staffed restaurant, and every food critic in Paris. If Remy commands it, he could assemble an army that would tear apart Stuart Little and his family.
