You have to use a Moon Stone to make it evolve into Delcatty, it won't evolve on it's own.
You need a moon stone to evolve a skitty.
according to the official player's guide for Pokemon emerald version wild lunatone is the only Pokemon that hold moon stones and they can't be caught in emerald. You need to trade a lunatone over from sapphire.
In Emerald, the only Pokemon that evolve with a Moon Stone are Jigglypuff, and Skitty. Skitty and Jigglypuff both are normal-type Pokemon. Skitty can be found in Route 116, east of Rustoboro City, and they are very hard to find. Jigglypuff can be found in Route 155, north of Rustoboro City. Jigglypuff evolves into Wigglytuff, anf Skitty evolves into Delcatty.
munna
Skitty does not evolve by a level it evolves from a 'Moon Stone' which you can buy from the Store, give it to the skitty and it will evolve into a Delcatty
you need a moon stone to evolve skitty into delcatty.
skitty
Evolve a Skitty using Moon Stone. Skitty can be caught outside Rusturf Tunnel on Route 105 and Moon Stones can be traded over or found in Meteor Falls.
skitty does not evole by its self you need a moon stone to help skitty evolve into a skitit
catch a skitty at the gras between rustbory city and the rusturf tunnel if you got it let it evolve using a moonj stone
Nidorino, Nidorina, Jigglypuff, Clefairy, Lombre, Evee, Skitty, Growlithe, Pikachu, Exeggcute, Gloom, Weepinbell.
Skitty is capable of evolving at any level because it does not evolve according to level, you have to use a Moon Stone on it in order to evolve it into Delcatty.