When you decide to choose teal formal dresses for bridesmaids, some of the more mature members in your wedding party might not be best pleased with your bridesmaids if they're looking at the short dresses in the bridesmaids collections at your local bridal shop. Traditionally in a church wedding it's always been the norm to be fully covered, when dresses went from having long sleeves to going strapless it was considered risky and many older members of the wedding party were shocked at being seen in church with exposed shoulders. Times have changed however, many weddings are done in hotel venues rather than in the church, and to be fair if you turned up in a sleeveless dress these days to your local chapel, they won't think anything of it.
Short teal formal dresses are fine for modern weddings, they have become more acceptable in the last 10 years and it's quite normal to have shorter dresses. How short and the style of them tends to be the more important question these days. If they are shorter than mid-thigh then expect the older members to be a bit shocked! If they're fitted and short then this can be elegant or can be a bit too glamorous – it depends on the length. If you have more floaty skirts then too short will look like a babydoll nightgown, so go for around knee length or longer to avoid the shocked looks of your guests.