Well, I’ve finished the game without using Shuri as a general OR redeploying troops, so I still disagree. Certain generals can make certain battles much easier, but they’re still not as crucial as other factors (strategists, formations and troops distribution).
EDIT: I’ll specifically mention what I did against Enshou: Bachou as general, Chouhi (yes, Chouhi) as strategist. With Bachou’s Ougi, 60 in Light Infantry and repeatedly using Feint and Ambush, Enshou falls in EIGHT turns, and is only able to call for reinforcements once or twice. Substituting Bachou for another general (any of them, really) also works, because Feint and Ambush with Chouhi’s maxed bonus mows down over 2000 soldiers EVERY TURN even without any Ougi (or Ougi cancelling, as it were).
EDIT2: Shuuyu falls in 9 turns if you use Chouun as a strategist, dump everything you’ve got into Light Infantry, and just alternate between Rotating Charge and Gated Corral. Once again, ANY GENERAL WILL DO. I used Kan’u in this particular case, and I even screwed up a little in the preliminary battle, so my numerical advantage in the second battle could be even greater. It could be even less than 9 turns.