Tokugawa (Protective and Aggressive), starts with fishing and the wheel
Unique Unit is the Samurai (maceman with 2 extra first strikes, starts with drill, but requires iron rather than copper or iron) A strong UU to bridge between Classical era warfare and gunpowder
Unique Building is the Shale Plant (a Coal Plant that does NOT require coal, +10% production). Essentially eliminates the need for coal and it's oppressive pollution although the IronWorks is diminished.
Mad's Opinion: The game's best Gunpowder Era War-Monger!
Mad's Failed Tokugawa the Isolationist:
http://forums.civfanatics.com/showthread.php?t=263705
How to play with: (Master Turtle, Master mid-late game Warlord)
The games best military leader post gunpowder, free combay I/Drill I/City Garrison I post muskets coupled with a powerful late game UB makes Toku an obvious choice for late game military action. The difficulty is getting him to that point considering his traits and UB have no economic advantage aside from the protective fast wall whipping trick, and fast castles for the extra trade route. Do not fret, Tokus key to an economy is simple and standard beelining of early and classical economic techs. He starts with fishing and the wheel, thus he has a decent chance of working early commerce in seafood (if not, settle the second city near some) and can built some early trade routes. Thus I suggest teching agriculture and Pottery ASAP, then work on either mining/bronze or hunting/archery using combat I warriors for early defense. Avoid non-essential early rushes and wonders, be friendly (meaning DONT act like the AI Tokugawa) with open borders, and tech those economy techs such as sailing, writing, currency, Code of Laws. Once established, Civil Service and Machinery open up Samurai and protective crossbows. At this point you may want to consider military expansion using middle Age units or wait until the gunpowder era. Assembly Line should be prioritized though for the powerful Infantry units and the UB.
What to expect from AI Tokugawa (Favorite civic mercantilism). One of the more predictable leaders, expect nothing but problems. Toku is an isolationist and hes the most difficult to get open borders with, he rarely trade techs or resources, and usually makes a lot of demands that very poorly affect diplomatic settings if you refuse. Not to say hes impossible to befriend, just difficult and he will likely be your only one. However, once befriended he is very loyal and NOT a backstabber (well, mainly because he hates someone more), and will establish a defensive pact pretty easily at pleased, but usually, its not worth the effort or sacrifice unless you plan to have no tech trading partners. HE can be an exceptional attack dog at pleased as he is easy to bribe, however refusing to go to battle with him can result in severe negative diplo points. He is a classic war-monger, building a lot of well promoted units however he is a very poor techer and will soon be behind in tech and have an outdated (yet still dangerous) military. If he is close to you expect to go to war with him although he is very difficult to rush, if he is far enough away you may be able to simply ignore him. He is not much of a threat to win unless he gets A LOT of early land and has a monster empire.