That is a great situation for a flow:
1. create a flow from a solution
2. select the common data service current environment connector
3. Choose the when a record is created, updated, or deleted trigger
4. On your trigger, set the entity to lear, the trigger to when a record is created, and scope to organization
5. Next add a get record step--choose lead for the entity and select the Lead id from the when a record is created step for the record id.
6. Next add another get record step--choose team for the entity and owner as the record id from the first get record step.
Now you have everything you need. The email address is on the team and we now have the team record that the lead is assigned to.
7. Next send an email--you have two choices--the mail connector of the O365 outlook connector. I like the mail connector for general notification type emails because I don't need to mess with mailbox connections.
In the send email step, select the "to" field and select the email address field from the team. Enter in to the subject and description the desired message text, including dynamic references to whatever lead fields you want to include.
This assumes that you have an email address on the team record. Some people have crated a distribution list email address for the team and then use that for team notifications. Alternatively, you could add a step to list records of users linked to the team and then send an email to each team member.
