Gifted: Characters who demonstrate high reasoning ability, can master difficult concepts with few repetitions, and display high performance capability or notable mastery in intellectual or specific academic fields, which makes them equivalent to real-world experts in these areas.
Genius: Individuals with an exceptional capacity for knowledge and intelligence, usually in one area of varying depth. This level of intellect is the level of
real-world geniuses, polymaths, and genuinely extremely prominent intellectuals, and, in the absence of better feats, should be the default intelligence category for fictional characters with exceptional or superhuman intelligence.
Extraordinary Genius: Individuals whose knowledge spreads over multiple fields of science and who vastly surpass the real world's upper human limits. At this level, many are capable of creating extremely advanced futuristic technology, executing complex strategies even under high pressure, outperforming supercomputers, and even accurately predicting the future through sheer mental calculations.
Supergenius: The highest level of non-omniscient intellect, possessed by individuals with unfathomably superhuman intelligence who are capable of creating impossibly advanced physics-defying and reality-warping fantasy technology for extremely diverse purposes.
Take note that for a Supergenius rating to be given based on technological prowess, the character in question should be able to essentially warp reality as they wish on an at least universal (3-A) scale with their inventions, or even use them to overpower tier 1 entities for higher cases.