How do I fix this Auto Uniform Script?

I've attempted to create a auto uniform script. It doesn't seem to want to work for some reason. Would anyone be able to fix this for me please?

print("Uniform Script Loaded Sucessfully!!")
local baseurl = "http://www.roblox.com/asset/?id="
local clothingData = {{rank = 1, shirt = 137338539, pants = 154082705},
{rank = 2, shirt = 137338539, pants = 137338545},
{rank = 3, shirt = 137338539, pants = 137338545},
{rank = 4, shirt = 137338539, pants = 137338545},
{rank = 5, shirt = 137338539, pants = 137338545},
{rank = 6, shirt = 137338539, pants = 137338545},
{rank = 7, shirt = 144851570, pants = 144939229},
{rank = 8, shirt = 144851570, pants = 144939229},
{rank = 100, shirt = 144851553, pants = 144939305},
{rank = 150, shirt = 144851553, pants = 144939305},
{rank = 151, shirt = 144938162, pants = 144937798},
{rank = 170, shirt = 144938162, pants = 144937798},
{rank = 249, shirt = 144943553, pants = 156726468},
{rank = 250, shirt = 144943553, pants = 156726468},
{rank = 251, shirt = 144850883, pants = 156726468},
{rank = 252, shirt = 144850883, pants = 156726468},
{rank = 253, shirt = 144850883, pants = 156726468},
{rank = 254, shirt = 144850883, pants = 156726468}}

function newPlayer(p)
    if p:IsInGroup(869857) then
        p.CharacterAdded:connect(function(c)
            if not char:FindFirstChild("Pants") then
                Instance.new("Pants", c).Name = "Pants"
            end
            if not char:FindFirstChild("Shirt") then
                Instance.new("Shirt", c).Name = "Shirt"
            end
            local rank = p:GetRankInGroup(869857)
            for i=1, #clothingData do
                if v.rank == rank then
                    c.Shirt.ShirtTemplate = baseurl .. v.shirt
                    c.Pants.PantsTemplate = baseurl .. v.pants
                end
            end
        end)
    end
end
game.Players.PlayerAdded:connect(newPlayer)
for _,v in pairs (game.Players:GetPlayers()) do
    newPlayer(v)
end

1st, like MastaJames said, you need to either pick char or c since you're using both but only defined c (the parameter of the function).

Later, you forgot to define v in your iteration (v = clothingData[i])

At this point, I believe your script is working, except that, just like your loop to guarantee newPlayer is fired for players already in the place, you have to do the same thing for CharacterAdded or else this will only work after dieing once:

print("Uniform Script Loaded Sucessfully!!")
local baseurl = "http://www.roblox.com/asset/?id="
local clothingData = {{rank = 1, shirt = 137338539, pants = 154082705},
{rank = 2, shirt = 137338539, pants = 137338545},
{rank = 3, shirt = 137338539, pants = 137338545},
{rank = 4, shirt = 137338539, pants = 137338545},
{rank = 5, shirt = 137338539, pants = 137338545},
{rank = 6, shirt = 137338539, pants = 137338545},
{rank = 7, shirt = 144851570, pants = 144939229},
{rank = 8, shirt = 144851570, pants = 144939229},
{rank = 100, shirt = 144851553, pants = 144939305},
{rank = 150, shirt = 144851553, pants = 144939305},
{rank = 151, shirt = 144938162, pants = 144937798},
{rank = 170, shirt = 144938162, pants = 144937798},
{rank = 249, shirt = 144943553, pants = 156726468},
{rank = 250, shirt = 144943553, pants = 156726468},
{rank = 251, shirt = 144850883, pants = 156726468},
{rank = 252, shirt = 144850883, pants = 156726468},
{rank = 253, shirt = 144850883, pants = 156726468},
{rank = 254, shirt = 144850883, pants = 156726468}}

function clothePlayer(c,p)
	if not char:FindFirstChild("Pants") then
		Instance.new("Pants", c).Name = "Pants"
	end
	if not char:FindFirstChild("Shirt") then
		Instance.new("Shirt", c).Name = "Shirt"
	end
	local rank = p:GetRankInGroup(869857)
	for i=1, #clothingData do
		local v = clothingData[i];
		if v.rank == rank then
			c.Shirt.ShirtTemplate = baseurl .. v.shirt
			c.Pants.PantsTemplate = baseurl .. v.pants
		end
	end
end

function newPlayer(p)
	if p:IsInGroup(869857) then
		p.CharacterAdded:connect( function(c) clothePlayer(c,p) end );
		if p.Character then
			clothePlayer(p.Character,p);
		end
	end
end

game.Players.PlayerAdded:connect(newPlayer)
for _,v in pairs (game.Players:GetPlayers()) do
	newPlayer(v)
end