There is a common pattern in various mythologies - particularly in the Indo-European "big family" set - of gods overthrowing monsters and sometimes being overthrown in turn by a new generation of deities. Does this trope of divine succession have a name?
Yes and no.
I'm afraid, from what I know, there isn't necessarily a nice, clean term to encapsulate what you're looking for, especially not one that has survived since the age of the Indo-European language. However, I'll do my best to supplement this disillusionment with some information to steer you towards something similar.
Firstly, what you mention is most certainly an Indo-European mythological concept, but since the upheaval and replacement of cultures is ubiquitous across the world, it is not a unique concept. The invasions of Ireland, the war between the Greek Olympians and Titans, and the Aesir-Vanir War are all examples of this Indo-European myth that has spread throughout Eurasia.
The closest term to this "war-between-generational-gods" is "theomachy," simply meaning "god war" in Greek.
In other senses, it can be interpreted as intergenerational conflict, acculturation, colonization, and assimilation, for the basis of these myths is the emergence of new cultures and new gods, which symbolically wage war against and defeat the gods of the former culture. The most general approach to this is the agrarian vs. warlike peoples, as evidenced by the newer, warlike Aesir fighting the older, agrarian Vanir as well as the more agrarian Titans (Rhea and Cronus both had significant agricultural ties) fighting the more warlike Olympians that superseded them as rulers of the realm.
For further information, see the Crecganford channel for scholarly dives into Indo-European mythology. These two videos on giants and the oldest gods explain the prominence of this myth in fascinating depth.
Hope this helps a little, even if it's not the answer you're looking for. Have a fantastic day.