Fire Emblem: The Sacred Stones/Chapter 10: Revolt at Carcino

Seize the gate
The main priority is to go help Innes and his small mercenary group. Move your group down to the fort that the small group is in and split up. Have a small group of about 3 or 4 go to the right and fight off the bandits that come from the mountains. If this small group is strong, send your healer with the other group whether you have just one or more healers.

The larger group should head down toward Innes and should have either Tana or Erika to recruit him. Once you get there, talk to Innes and have him talk to Gerik first. It's your choice whether you want to recruit Tethys now or after the wave of enemies. If you talk to her early, you get to have one character take two moves in one turn or you can leave her safely in the fort and talk to her later. On the next turn, send either Innes or Neimi onto the ballista to get rid of the priest in Marisa's group. The priest has a sleep staff that will really hurt your plan for victory. Start bracing for the group that is heading it's way up, but keep an eye on Marisa. You should have Gerik in the front of the group, ready to talk to Marisa. The small enemy group will fall easily but once you recruit Marisa, reinforcements are going to come in the form of 4 pegasus knights and 1 falco knight from the bottom left, and 3 cavaliers and 1 ranger from the bottom right. Once it's all clear, regroup with the others and head toward the gate.

The two archers near the boss will shoot their ballista wildly at your party so have someone soak up the shots until they run out of ammo. The myrmidon next to the two archers has a red gem that he won't drop. If you want it, have Colm go in and steal it, rescuing him afterwards so that he doesn't take too much damage. Take out the enemies and go for Pablo.

Boss: Pablo
Send someone in with high resistance to fight Pablo as he can really hurt anyone who doesn't. Anima magic can help so send in a mage or sage to take him out easily. Either that or send in a strong physical unit that won't die from his attacks to attack, having someone go in and heal them and then have Tethys dance so that the healer can move out of Pablo's range. He will drop a Guiding Ring for a magic or staff user to use.

Another, simpler strategy is to give the long bow to Innes and let him shoot Pablo down from beyond his range.