Build Lineup is a formation creator app for soccer lovers. While being free, it's highly customizable and offers many features:

Easily drag and drop players to change their positions, or simply choose a football formation template.
Edit player name and jersey number.
Add a sub to player.
Add an arrow to players to show the area of influence.
Create 5-a-side, 6-a-side, 7-a-side, 8-a-side, 9-a-side, 10-a-side, or a classic lineup with 11 players.
Change team jersey colors. You can also choose different colors for your goalkeeper or other players by tapping them and clicking Jersey tab.
Choose a field color.
Choose jersey type: Plain or striped.
Download your lineups as images. This will save your lineups in camera roll, so that you can share them easily!
Store your plays in a list with the ability to edit and copy them. This makes it especially easy for football coaches to reuse roster details. No need to enter squad details each time you design a lineup for your team.