Skeletron is one of the 3 pre-hardmode bosses in the game Terraria. Unlike other bosses,it can only be defeated once on a world.In order to fight it again,you must go make another world and head to the dungeon. This will tell you the strengths, weaknesses, and how to fight Skeletron.
Strengths: Is the 2nd strongest pre hard mode boss, has 3 components, high health, many attacks, high damage.
Weaknesses: Loses all defense in the head when spinning, tends to hover above the player and use its hands for attacking.
Arena: 5-10 rows of Wooden Platforms 10-20 blocks wide.
Potions: Healing, Regeneration, Archery, Ironskin, Mana(if using magic)
Weapons: Best Sword you can get your hands on, Minishark or Phoenix Blaster, and Molten Fury.
The Fight! Begin by spamming your gun at his head, when he comes to spin attack either aim for his head with your bow or hit it with your sword. After he is down to half health just use your gun and you should win.