make me a roblox lua script that needs to be put inside a dummy for it to move, as if like an AI inside it.

Sure, here's a simple example of a Roblox Lua script that could be used to move a dummy around. This script will make the dummy move forward and backward in a straight line.

-- Get the dummy
local dummy = game.Workspace.Dummy

-- Set the dummy's primary part
dummy.PrimaryPart = dummy.HumanoidRootPart

-- Set the dummy's initial position
local initialPosition = dummy.PrimaryPart.Position

-- Set the distance the dummy should move
local moveDistance = 10

-- Set the speed the dummy should move
local moveSpeed = 1

-- Create a loop to move the dummy back and forth
while true do
    -- Calculate the target position
    local targetPosition = initialPosition + Vector3.new(moveDistance, 0, 0)

    -- Move the dummy to the target position
    dummy:MoveTo(targetPosition, moveSpeed)

    -- Wait for the dummy to reach the target position
    while (dummy.PrimaryPart.Position - targetPosition).Magnitude > 1 do
        wait()
    end

    -- Swap the initial and target positions
    initialPosition, targetPosition = targetPosition, initialPosition
end

Please note that this is a very basic script and may not work perfectly in all situations. For example, it doesn't take into account any obstacles that might be in the dummy's path. You may need to modify it or use a more advanced script for more complex movements.