Personally I felt Sharla wasn't right for the final parts of the game. To me, it's more important whether the characters I use fit the story, so I used Shulk, Dunban and <spoiler>, but roleplaying aside, she's not that useful in battle either since all the characters can easily keep their HP up without any healer help, through Skills(healing by encouraging is a must), gems like Arts Heal and their own healing skills.
I used Sharla in the fights related to her though. Also I kept Gadolt's Rifle on her the whole way through because it feels right.
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