xmenevolution

With the Fire Stone, you can evolve Vulpix into Ninetales, Growlithe into Arcanine and Eevee into Flareon.
With the Water Stone, Poliwhirl into Poliwrath, Shellder into Cloyster, Staryu into Starmie, Eevee into Vaporeon and Lombre into Ludicolo.
With the Thunderstone: Pikachu into Raichu and Eevee into Jolteon.
With the Leaf Stone: Gloom into Vileplume, Weepinbell into Victreebel, Exeggcute into Exeggutor and Nuzleaf into Shiftry.
With a Moon Stone: Nidorina into Nidoqueen, Nidorino into Nidoking, Clefairy into Clefable, Jigglypuff into Wigglytuff and Skitty into Delcatty.
With the Sun Stone: Gloom into Bellossom and Sunkern into Sunflora.

The reason your Seadra didn't evolve is because the item it should have been holding was a Dragon Scale and not a King's Rock.

Now here's the list of Pokemon that evolve with a trade and the items they should hold.

Kadabra, Machoke, Greveler and Haunter with no item to get Alakazam, Machamp, Golem and Gengar respectively.
Poliwhirl and Slowpoke with a King's Rock to get Politoed and Slowking
Onix and Scyther with a Metal Coat to get Steelix and Scizor.
Seadra with Dragon Scale to get Kingdra.
Porygon with an Up-Grade to get Porygon2
Calmperl with a Deepseatooth or with a Deepseascale to get Huntail or Gorebyss.