Load conditional logic data in custom field


How can i load conditional logic data to custom fields?
For example there are 2 custom fields both are Select type, League and Team.

When I choose League, the team list for the Team field will show only teams that related to the league that chose earlier.


If its impossible to do it, how can i create a field that is when I type, it will auto suggest based on data or options that is inserted earlier? What kind of custom field is this?

You can write custom script for that. Refer below code from Customize Form which dynamically displays field names in Sort Field based on doctype chosen on customize from.