All known pokemon revived from fossils are at least partly rock type. What are the prevailing theories as to why this is and which do you most agree with?

There are actually two prevailing theories at the moment, anon:

1. Although studies have shown that steel-type pokémon are sturdier, rock-types are quite famous for their ability to withstand an incredible amount of weathering. Considering the fact that kabuto still exist, it is therefore generally thought by the supporters of the Type Theory that the ancient pokémon we know today were all rock-types, and they were such because of specific conditions—such as, perhaps, more extreme weather—that forced them to adapt rock-based features in order to withstand their environment. This is certainly true for the kabuto, which has only survived for this long purely because its rock shell deters predators and because that same rock shell weighs just enough to force a kabuto to develop a level of hardiness not present in non-rock-types.

2. The second theory assumes that not all fossil pokémon were rock-types. For example, there are theories that state that tirtouga and carracosta were never actually rock-types but rather pure water pokémon. Likewise, amaura might have been purely ice or ice/dragon, shieldon might have simply been steel or steel/ground, and so forth. However, during the most common fossilization process for pokémon, gaps of gas or liquid throughout an organism’s body is filled with mineral-rich water that is then compressed and settled, forming rock. As the fossil resurrection process is still new, it is often thought that the pokémon born from this technique are not accurate representations of their ancient counterparts but instead half their original species and half the rock that had encased them. The fact that the half-rock kabuto still exists is purely coincidental.

As for which theory I support, I tend to lean more towards the latter than the former. In most regions, the fossil resurrection process is not done via cloning, as one would assume, but rather via organic conversion—or, in layman’s terms, the pokémon is put back together via a machine. Which, from my own extremely scientific standpoint (and certainly not experience, of course), is a process that I can safely say not everyone can get completely right.