Unless you are not a prohibited person, it is perfectly legal to open carry or conceal carry a Taser in California except in the usual locations(courts, airports etc.) No permit required, though it is a good idea to get certified in the use of one, just incase you have to go to court for tasing someone.
If you are going to get one, you should spring for the X26c. It's smaller, lighter and the trigger pull is not as heavy as on the M26c or if you have money to spend get the new X3. You can tase 3 people without having to reload. The X3 Pros and Cons:
Pros: 3 shots back to back if needed, 2 lasers that show you where each prong will hit. There's more pros but I'm too tired to list.
Cons: it will set you back about $1800 and it's on the bulky side.