Suddenly is an adverb and its comparative is formed by putting the word "more" in front of it.
It is most suddenly and most suddenly
more suddenly, most suddenly
"Suddenly" is an adverb that cannot be compared using the comparative form. It describes how an action or event occurs unexpectedly or quickly, and it does not have degrees of comparison like other adverbs (e.g., "quickly," "more quickly," "most quickly").
The comparative form of dreamy is dreamier
The comparative form of many is more
The comparative form of "softly" is "more softly."
The comparative form of good is better.
"Truer" is the comparative form of true.
The comparative form of handsome is handsomer
The comparative form of solid is solider
The comparative form of sunny is sunnier.
The comparative form of full is fuller
The comparative form of "central" is "more central."
The comparative form of busy is busier.