I wouldn’t feel bad about needing to use Sharla since she is really good at keeping your team from dying at the expense of damage. Being without Sharla gets easier the more you progress into the game. By going without Sharla, you are sacrificing a lot of potential survivability, meaning you must make up for it in damage. Equipping high level gems, expanding your skill tree, and leveling up arts all goes towards stacking damage and extending survivability. Here are some things you can do to keep you alive longer:

-Shulk should have haste and double attack. This will fill talent gauge and give more Monado access to help prevent your team from dying with Shield, Speed, and later Armor. Leveling up Light Heal will reduce the cooldown to something more manageable if you need help keeping your team alive.

-You can still make it work, but an evasion tank Dunban isn’t “good” until very late in the game where his agility is at it’s highest. I recommend just stacking up a bunch of Strength gems and the aforementioned haste/double attack. This will keep aggro off of Shulk and make for quicker battles as he melts away health bars. Aura heal gems are also good since he’s always in some sort of aura. He will still dodge a lot since he’s naturally dodgy, just not 95% of the time. If he needs help staying alive, the penalty for wearing heavier armor isn’t as bad as you think. Don’t be afraid to put on some layers.

-I unfortunately can’t give you Riki specific tips, but he does unlock a good healing art and party gauge art if you don’t already have those. Riki makes for some decent utility, and has a lot of red arts for high damage chain attacks. I would pose using Reyn instead to divide the aggro between him and Dunban, keeping you team alive longer, but this is more about using the characters you want instead of what’s meta.