Neverused pokemon are pokemon that are never used by trainers due to the fact that they are not at all powerful. Pokemon in this battle tier are:
Ariados, Beautifly, Beedrill, Bibarel, Castform, Chatot, Chimecho, Corsola, Delcatty, Delibird, Ditto, Dustox, Exploud, Farfetch'd, Furret, Glalie, Huntail, Illumise, Kricketune, Ledian, Luvdisc, Magcargo, Masquerain, Mawile, Mightyena, Minun, Mothim, Noctowl, Pachirisu, Parasect, Pelipper, Phione, Pidgeot, Plusle, Seaking, Spinda, Sudowoodo, Sunflora, Torkoal, Tropius, Unown, Venomoth, Volbeat.
Pokemon in the NU class can be used in any contest but only NU class pokemon can be used in NU contests.
Any pokemon that you did not see in these guides are not in classes because they have more powerful evolutions.