NULLUS & CO.
There are nine adjectives in Latin with an important peculiarity. Even these are mostly normal. Most of their endings conform to the style of standard group 1 adjectives (magnus, magna, magnum etc). Two cases may trip you up, however. The genitive singular ends in –ius, not –i or –ae, and their dative singular is in –i rather than –o or -ae.
This matters when you meet a word like, for instance, nulli. You could mistakenly translate this as the genitive (nobody’s) rather than the dative, to nobody.
The tricky nine adjectives are unus (one), ullus (any), nullus (no, none), solus (only), totus (all), uter (either), neuter (neither), alter (another), and alius (other).