Leaderboard Script Broke?

game.Players.PlayerAdded:connect(function(Player)

	function Leaderstats()
		leaderstats = Instance.new("IntValue")
		leaderstats.Parent = Player
		leaderstats.Name = "leaderstats"
	end

	function PowerLevel()
		PowerLevel = Instance.new("IntValue")
		PowerLevel.Parent = Player:FindFirstChild("leaderstats")
		PowerLevel.Name = "Power Level"
	end

	function Attack()
		Attack = Instance.new("IntValue")
		Attack.Parent = Player:FindFirstChild("leaderstats")
		Attack.Name = "Attack"
		Attack.Value = 25
	end

	function Defense()
		Defense = Instance.new("IntValue")
		Defense.Parent = Player:FindFirstChild("leaderstats")
		Defense.Name = "Defense"
		Defense.Value = 25
	end

	function Agility()
		Agility = Instance.new("IntValue")
		Agility.Parent = Player:FindFirstChild("leaderstats")
		Agility.Name = "Agility"
		Agility.Value = 25
	end
	
	function Energy()
		Energy = Instance.new("IntValue")
		Energy.Parent = Player:FindFirstChild("leaderstats")
		Energy.Name = "Energy"
		Energy.Value = 25
	end

	function Rank()
		Rank = Instance.new("StringValue")
		Rank.Parent = Player:FindFirstChild("leaderstats")
		Rank.Name = "Rank"
		Rank.Value = ""
	end
	
	function SetValue()
		leaderstats = Player:FindFirstChild("leaderstats")
		PowerLevel = Player.leaderstats:FindFirstChild("PowerLevel")
		Attack = Player.leaderstats:FindFirstChild("Attack")
		Defense = Player.leaderstats:FindFirstChild("Defense")
		Agility = Player.leaderstats:FindFirstChild("Agility")
		Energy = Player.leaderstats:FindFirstChild("Energy")
		Rank = Player.leaderstats:FindFirstChild("Rank")
		
		PowerLevel.Value = Attack.Value + Defense.Value + Agility.Value + Energy.Value
	end
	
	Leaderstats()
	PowerLevel()
	Attack()
	Defense()
	Agility()
	Energy()
	Rank()	
	SetValue()
		
end)

The output focuses more on

	function SetValue()
		leaderstats = Player:FindFirstChild("leaderstats")
		PowerLevel = Player.leaderstats:FindFirstChild("PowerLevel")
		Attack = Player.leaderstats:FindFirstChild("Attack")
		Defense = Player.leaderstats:FindFirstChild("Defense")
		Agility = Player.leaderstats:FindFirstChild("Agility")
		Energy = Player.leaderstats:FindFirstChild("Energy")
		Rank = Player.leaderstats:FindFirstChild("Rank")
		
		PowerLevel.Value = Attack.Value + Defense.Value + Agility.Value + Energy.Value
	end
	
	Leaderstats()
	PowerLevel()
	Attack()
	Defense()
	Agility()
	Energy()
	Rank()	
	SetValue()
		
end)

Output:

zars15's CFrame loaded 22:16:03.684 - ServerScriptService.Leaderboard:59: attempt to index global 'PowerLevel' (a nil value) 22:16:03.685 - Stack Begin 22:16:03.686 - Script 'ServerScriptService.Leaderboard', Line 59 - global SetValue 22:16:03.687 - Script 'ServerScriptService.Leaderboard', Line 69 22:16:03.688 - Stack End 22:16:03.689 - Disconnected event because of exception 22:17:32.284 - Auto-Saving...

I dont know if this is going to help but when you define PowerLevel as a child of Player you are finding it in game.Players.PLAYERNAME.PowerLevel and unless this is your proper intention to have it here there that is why it has a nil because it might not exist there. This is just an answer for the first problem.

I highly suggest you do not create a function for each value. Instead, create one function for all of them. Also, I suspect that you get the PowerLevel output error because you are searching for PowerLevel before it actually comes into existence. Before I provide a code fix, may I ask whether or not the script actually inserts the values into the Player or not? (If you don't know how to check, start a Solo Server, not play solo, and then go into the Player in the players menu and check if the values are there or not.)