Seadra can be evolved at any point in the game; to evolve it into a Kingdra, you must first get a Dragon Scale and give it to him/her. Then you must trade it and voila, your Kingdra.
you have to trade a seadra while it is holding a dragon scale
It evolves at level 32.
train it to lvl 38 and trade it then pickaboo it will evolve into kingdra
Horsea evolves into Seadra at Level 32 in Pok
Seadra evolves into Kingdra at level 45.
Staryu does not evolve by level. You use a water stone to make it evolve.
Ralts will evolve at level 20 into Kirlia. From there it will change into a Gardevoir at level 30. However, in Emerald version you can not evolve Kirlia into Gallade
Lairon evolves at level 42-45 in Pokemon Emerald version.
Seadra can never level up to evolve. You have to trade it when it is holding a Dragon Scale item. - Pokemon Guru
Seadra will only evolve during a trade while it holds dragon scale.
Rhyhorn evolves into Rhydon at level 42 in Pokemon Emerald Version.
Slugma evolves by Level at Level 38. It evolves into Magcargo.