Based on the search results, it seems that Prodigy is a game that involves battling monsters with different elemental strengths and weaknesses. However, there is no clear answer to what lightning is weak to in Prodigy. Some of the search results provide information on the weaknesses of other elements, but lightning is not mentioned specifically.
According to, fire is weak against water, water is weak against storm, storm is weak against ice, and ice is weak against fire. also mentions that fire pets are weak to water but strong against storm. However, there is no mention of lightning in either of these sources.
It is possible that lightning is not a separate element in Prodigy, or that it is not included in the list of elements that have clear strengths and weaknesses. Without more information, it is difficult to provide a definitive answer to this question.