Hi,
tl;dr: Issue is solved by using business rules.
Explanation:
So my first hunch you can read here, turned out to be the case; Tickets created via API, will follow the behaviour rules set for agents. Which makes perfect sense, as the API is just another “form” of an agent. To not turn off these field requirements for all agents, you can use business rules to negate this requirement per agent (or per whatever you seem fit).
How:
Login to your freshservice portal with an administrative account.
Go to Admin → Business Rules For Forms → Create New Rule
Enter a name to identify the rule, and fill in the options per below screenshot
Scroll down to conditions and actions and fill in accordingly. Especially with the Actions is where the magic happens:
The above business rule is currently set to not require a group and agent when a ticket is created using my account (via the portal or via API).
Our next challenge is to create a special agent account, that is not tied to a specific person, but we will figure something out.
By the way, I was pointed to this solution by the Freshdesk service desk, which described in detail how things worked and how to setup the business rule! Thank you all for taking the time to troubleshoot this issue.
I do want to recommend to get some sort of note in the API V2 documentation, regarding the above. 