End Event Script Not Working?

First, two important issues: 1: tab your code correctly; 2: use meaningful variable names:

function EventEnd()
	game.ServerStorage.Mode.Value = "None"
	game.Workspace.MapHolder:ClearAllChildren()
	local players = game.Players:GetPlayers() -- Use GetPlayers, not GetChildren
	for i = 1, #players do
		local player = players[i]
		player.leaderstats.Kills.Value = 0
		player.leaderstats.Deaths.Value = 0
		if player.TeamColor == BrickColor.new('Really red') or BrickColor.new('Really blue') then
			player.TeamColor = BrickColor.new('White')
			wait(0.1)
			player:LoadCharacter()
			TeamOne = 0
			TeamTwo = 0
		end
	end
end

Now, let's look at the condition.

It turns out that or is lower precedence than *==. That means how this evaluates:

if (team == red) or blue then

that will always be "true" since if team == red is false, blue is "true enough" and the condition will pass (or takes the "truer" of the two)

If we put parenthesis:

if team == (red or blue) then

This wouldn't work either. (red or blue) is just red -- you can't have one expression have two values.

You have to be explicit:

if team == red or team == blue then

(I am using some "pseudo code" here, e.g. red, team and blue to keep things a little shorter and clearer -- this isn't the actual code you would type)