The Superlative of the Verb is base on the syllables and compatibility of the pronunciation of the verb.
Example:
Intelligent - has 3 syllables, that's why "Most Intelligent" is its Superlative. (You put "most" before the verb to make it in Superlative Degree.)
Smart - has 1 syllable, that's why "Smartest" is its Superlative. (You connect -est after the verb to make it in Superlative Degree.)
Note:
Try to pronounce the possible Superlative word for the given word. If it's good to hear, it's correct. If not, it's wrong.
