It’s actually relatively trivial, in my own research I stumbled across a few threads but none of them had found a solution, all you need to do is locate the desired animation object from within the ‘Animate’ script and change its ID. The following script changes the default run animation to the ninja run animation.
local Game = game
local Players = Game:GetService("Players")
local function OnPlayerAdded(Player)
local function OnCharacterAdded(Character)
local Animate = Character:FindFirstChild("Animate") or Character:WaitForChild("Animator")
local Run = Animate:FindFirstChild("run") or Animate:WaitForChild("run")
local RunAnimation = Run:FindFirstChildOfClass("Animation") or Run:WaitForChild("RunAnim")
RunAnimation.AnimationId = "rbxassetid://656118852"
end
Player.CharacterAdded:Connect(OnCharacterAdded)
end
Players.PlayerAdded:Connect(OnPlayerAdded)