We use alternates on our level 5 team and they have to come to every practice with us. Just in case we ever needed them and so that they could learn our routine in case someone got hurt. Our alternates are usually on another team in our gym. This past year we had 4 alternates. 1 girl was on our level 5 team the year before but got injured and wasn't cleared till around October so we made her an alternate so she could still be part of the team and work out with us. 2 other ones were on our level 4 team. And the other girl used to be at a different gym and was just taking privates at our gym and we saw her and asked her to be an alternate on our team.
Good thing we had them because during the year we used 3 out of the 4 alternates in most competitions. 1 flyer had a season ending injury in February so we used our flyer alternate the rest of the year. another base had to get surgery in January so we used a base alternate for her for the rest of the season. And another base on our team got a concussion and was out for 2 months so we used a base alternate for her.