Widget, the World Watcher (1990)?
From IMDb:
Widget is an alien that has come down from the sky to learn about humans with the aid of his sidekick, Brain. They explore the world and educate kids on health, safety, emotions and dangers.
Found with the Google query cartoon alien "in * watch" site:imdb.com/title which returned this review:
Anybody that hasn't ever seen this, here's the scoop: This alien comes to earth dedicated to protect the planet. He's purple, he can morph,and can even talk to animals. His pals? Two earth brothers and a overactive head and hands called MegaBrain that lives in a watch on Widget's wrist.
Anybody that hasn't ever seen this, here's the scoop: This alien comes to earth dedicated to protect the planet. He's purple, he can morph,and can even talk to animals. His pals? Two earth brothers and a overactive head and hands called MegaBrain that lives in a watch on Widget's wrist.
