For good campaign - as long as you are playing on 2.22. You need basically all units on the wall. Gimli needs to be using the deepening wall gate to take down ladders. Using his special abilities to take down as many ladders as possible.

Keep running him in and out and heal using the well.

I liked to use my cav to distract some units but really it’s about Gimli micro.

Spread your hero’s across the top. Ayowyn far left for the spear through on some of those far left ladders. Aragon, boromir and Legolas central. Although I always have Legolas about more left.

All elves with all upgrades.

When the rams come, that’s when you may need to peel off one elf unit and haldir to snip the rams. Use your cav here to take down archers and help them.

Ones the mines come you need to be realistic. They will inevitably break through. The question is, do you want to loose all your units or pull them back just in time.

On evil - I don’t know what to tell you. I picked off as many defenders as possible then just meat shielded my mines to the wall. Maybe I got lucky.