How to find the number of players on a Team?

This may sound odd, but you don't even have to use the teams service in this script.

blue = 0
red = 0
for _,v in pairs(game.Players:GetChildren()) do
    if v.TeamColor.Name == "Bright red" and v.Neutral == false then
        red = red + 1
    elseif v.TeamColor.Name == "Bright blue" and v.Neutral == false then
        blue = blue + 1
    end
end

print("There are "..red.." players on the red team and "..blue.." players on the blue team.")

As you can see above, I have a script that gets all of the players in the game, and runs that code for each of them. I have values being added to that respond to the team. Also note my if statement saying "and v.Neutral == false". What that does is check if the player is even on a team. If they are neutral, they are ignored. If you want, you can make the script react to players being neutral like so:

blue = 0
red = 0
neutral = 0
for _,v in pairs(game.Players:GetChildren()) do
    if v.TeamColor.Name == "Bright red" and v.Neutral == false then
        red = red + 1
    elseif v.TeamColor.Name == "Bright blue" and v.Neutral == false then
        blue = blue + 1
    elseif v.Neutral == true then
        neutral = neutral + 1
    end
end

print("There are "..red.." players on the red team and "..blue.." players on the blue team. "..neutral.." players are neutral.")

There ya go! --XanthicDragon.

A more generic way of doing this is to write a function that returns a table of the players on a specific team. Using this table you can, for instance, teleport everyone on the team named "Blues" to a specific location as well as determine the number of players on the Blues team by using the # operator.

The following function returns tables with player's names instead of userdata.

function getPlayersOnTeam(...)
    local teams = {}
    for _, teamName in pairs{...} do
        local team = game.Teams:FindFirstChild(teamName)
        if team then
            local playersOnTeam = {}
            local teamColor = team.TeamColor
            for i, player in pairs(game.Players:GetPlayers()) do
                if player.TeamColor == teamColor then
                    table.insert(playersOnTeam, player.Name)
                end
            end
            table.insert(teams, playersOnTeam)
        end
    end
    return unpack(teams)
end

Applying this function:

local blues, reds = getPlayersOnTeam("Blues", "Reds")

local numberOfBlues = #blues
local numberOfReds = #reds

print("There are "..numberOfBlues.." players on Blues and "..numberOfReds.." on Reds")
print("The players on Blues include: "..table.concat(blues, ", "))

The previous code should output something like this:

There are 3 players on Blues and 2 players on Reds
The players on Blues include: name, name2, name3

Moving everyone on Blues to a specific location:

local blues = getPlayersOnTeam("Blues")

for _, playerName in pairs(blues) do
    local player = game.Players[playerName]
    if player.Character then
        player.Character:MoveTo(Vector3.new(0, 0, 0))
    end
end