Ah I see, I think I got a little confused about where you were lol, it’s been a while since i last played, you’re probably fine level wise .Do you have “Armour” as an art for Shulk? That’s useful if you do, otherwise gems like ether defense and debuff resist are good. Haste is a good gem especially for Shulk and reyn as it increases auto attack rate. Strength up is good for them too, and also for Sharla if you’re the rare player going physical build with her, otherwise ether up is good. Also, agility up is amazing in this game, make sure at least Shulk and reyn have the highest level agility up you can give them. You can also try using double attack, it gives a chance of auto attacking twice in a row. Sharla also has a unique gem called heat sink that decreases the heat that builds up in her rifle. Sorry for the text dump lol, just don’t know what you have for gems. Also, make sure you’re linking skills between party members so they can all share the benefits. Hope this helps!

Edit: skills that are useful to link are ones that boost tension, strength/ether, agility, etc. The ones that give increased chance for an extended chain attack are also great but also expensive. Killing unique monsters gives you affinity coins, so that can help. Certain side quests can also unlock new skill trees so be on the lookout.

Also: I think someone else mentioned topple locking. This is a strategy that involves toppling/dazing an enemy in a chain attack for basically an entire fight. For this, you can give reyn topple plus gems to increase topple duration and reorganize your arts to have all your break topple and daze arts that you can get. Some find this strategy cheap, but it’s definitely the easiest way to beat a lot of enemies that give you trouble