How to auto populate fields based on an entry?

How to auto populate fields based on an entry?

I seem to run into brain fade right when I need the answer most.  And when I'm about to go out of town.  Thus I'm asking an easy question that I can't find through forum/help searches.

I have one form that starts with a radio button with 5 possible choices (called "Team").  The following fields should be auto populated based on the response to to Team:

Team_Head_Coach (5 possible values)
Team_Coach_Email (ditto)
Team_Coach_Phone (ditto)

If a new record is being entered and the user choose "Team 1" then I want the 3 Coach fields to be filled in with the associated values for that Team.  If an existing record is updated (moving to a different Team) then the other 3 values need to change as well.

The list isn't getting any bigger than 5 so I'm OK with hard coding the IF/THEN conditions but if it makes more sense to create a separate form or forms to do this then that's OK as well. Please be explicit in your responses - thanks!  And the examples online aren't helping me so if you can use my specific input above that would be excellent!