In the recent "How do you want to see RPGs progress?" thread, a suggestion by /u/JamesTheSkeleton intrigued me. Basically, in order to facilitate GMs running games, he wanted the ultimate collection of monster stat blocks, where the same monster was basically statted for every game.

Obviously, that's completely infeasible. There are umpteen thousand different TTRPGs out there, and even discounting those that don't use stats blocks for monsters, there are way too many. But something in a similar vein that could still be useful to a massive number of people is possible and, because I apparently never tire of taking on long-term projects, I'm considering giving it a shot.

My question is twofold:

First, what would be the best way to determine which limited number of games should be included in such a compendium? Obviously, various editions of D&D and Pathfinder would be in the mix. But is there a feasible list somewhere (and I don't just mean Boardgamegeek's voted "rankings") that would indicate which games are the most played and therefore likely to be of use?

Second, there is a not-insignificant number of games out there where stat blocks are not used but the information of a stat block could be useful to GMs and players that have to improvise. Some of this is obvious (size, weight, physical description, movement, methods of attack) and some of it may be less so (morale, social organization, etc.) Is there a resource online that might shed some light on the most common or ubiquitous needed information for generalized stat blocks?