What Qualifies as Underused?
The current tagline (______ TF: < 25 results) is kind of a misnomer. Twenty-five is not always the limit to how many transformations an underused subject could be in. However, the amount is a major factor, as well as how many transformations are art, not stories (or vice versa). As for multi-TFs, I would judge them by the least common subject. A multi-TF into a Pokémon common in stories and one uncommon in stories is acceptable.
Underused vs Uncommon
Uncommon simply means not common, and underused means not common enough. But while I won't deny the clear difference between both words, I choose not to let it play an impact on this group. While one artist may view a certain subject as underused and another as just uncommon, vice versa is just as frequent for others. For example, many would argue that an obscure character with little TF representation can be more justifiably underused than a Pokémon with equal representation, but in our context that opinion is completely subjective. After all, if a subject can make a good transformation and isn't used much, it's underused!