Amazon EMR now supports up to thirty instance type configurations in Instance Fleets

You can now specify up to 30 EC2 instance types for each of your master, core, and task node groups when using EMR Instance Fleets with allocation strategy. Previously, this was limited to 15 for tasks nodes, and only 5 for master and core nodes. This increase allows you to specify a broader range of instance sizes, generations, and families that your workloads can operate across to improve your access to both Spot and On-Demand capacity.

Source:: Amazon AWS