The word "I'll" does not have comparative and superlative forms, because it is not an adjective. "I'll" is a contraction for "I will".
Ill, more ill, most ill.
ill- worse- the worst
It can be. The more common comparative is "more ill."
She is as ill as that man. He is the illest man among all.
The comparative degree of "holy" is "holier."
Teapot is a noun and, as such, does not have a comparative degree.
The comparative degree is wider.
"Less" is the comparative degree of little.
Thriftier is the comparative degree of thrifty.
The comparative degree for "lush" is "lusher."
The comparative degree of "light" is "lighter."
better for its comparative and best for its superlative