Yes, they'll be at the beginning 2nd grade reading level (RL 2.0-2.4). So, you can go right into the Emerging Reader's Set. The Emerging Reader's Set is a 14 book set with choice of Bible. For your readers that are not quite as confident, you'll want to pick the Early Reader's Bible as it is easier (RL 2.0) and has a more controlled vocabulary. For your more confident readers, they can begin with the "Beginner's Bible" (RL 2.4). It does not have a controlled vocabulary.
If you desire to only pick one Bible, I'd pick the easier one to make sure they all have a wonderful transition!
Blessings,
Carrie