@mbosc, Tournament creatures often take about a year plus to cycle through but that may go up since there’s more of them now. There’s a new event starting this week for Trodon. It is not yet clear how this will develop.
Regarding the VIP only creatures, they cannot be unlocked. The lower ones are available in the Solid Gold Pack at random for 10,000 loyalty points to anyone, someone they appear in the harbor for that or other amounts as individuals. To be sure you get a specific low end VIP you can use 20,000 Loyalty points when they are available. The high end VIPs are available for 50,000 loyalty for a few weeks at a time each. The Prize Drop has both Tournament and VIP creatures in the Gold and Diamond prizes respectively. Getting them as a non VIP is quite difficult without spending significant amounts of real world money. Getting them as a VIP directly in the drop is possible but against the odds. Getting the higher odds creatures in the Prize Drop wheels is guaranteed if you can build up enough points before timeout.
Hope that helps