Here is where caution is mandatory. Searching for Pokemon Tower Defense 3 Hacked Full Version exposes you to:
Hacked versions often have unstable scripts. You might invest 20 hours into a hacked save, only for it to crash permanently at the Elite Four. Pokemon Tower Defense 3 Hacked Full Version
The official PTD3 trading and leaderboards are long dead, but some hacks attempt fake online modes that steal your IP address. Here is where caution is mandatory