In your tablet definitions of your cluster .yaml file(s), you can specify a different container for the database. You will need to do this for each replica in a shard.
You will add a `datastore` field and populate it with a `type` and a `container`.
The only requirement for this is that the container needs to have a standard MySQL deployment. For example, the following block should work to set up Percona for your datastore:
- type: "replica"
datastore:
type: mysql
container: "percona/percona-server:5.7"