I'm trying to max out the level of all Heroes to get the Achievement: Completist.
I'm not sure if I have to only max out heroes I can play in story mode, or all heroes. Does this affect the strategy? Is there one for story characters, and one for non-story characters?
There's an eHow article outlining one method (however you need a level 50 character to utilize it):
Bring one character up to level 50. That's as high as you can go, so your character will have all their abilities. Ideally, you'll want to level a character that has a powerful Area of Effect attack. Yue Ying, Sun Shang Xiang, Diao Chan and Zhen Ji all work well. Of course, the best is Lu Bu, since he has the highest stats of any character.
Train a pair of horses that have the Find Weapon ability. This isn't hard to get and if you've played the game for more than a couple hours, you've probably already got at least one. Make sure one of them is very fast, with a speed of 400+.
Take your level 50 character and whoever you want to power level to the Battle of He Fei Castle, Wei side. Make sure your level 50 character is set as Player 2. Set the difficulty to Hard or something higher in order to get the best results.
Have Player 1 ride around and attempt to prevent the enemy from taking any of the objectives. At a minimum, ride in circles so you don't die.
Have Player 2 (your uber character) ride down and attack Sun Quan as quickly as possible. He has a swarm of officers around him, so beware. If you manage to kill him quickly, you will both get a boatload of XP and some of the best weapons to be had!
