Well, each generation there is a net of say 120 new pokemon.. each tier seems to run about 40 main pokemon, usually less for ubers, a little more for the others. Then say maybe 4 in each borderline tier. If we take Ubers, OU, UU, LU, NU, LC, LC UU as being able to accomodate 50 each, then we have only used about 300 or so of the available pokemon, maybe more. I've probably made some underestimates, and there's BL and even if I went with 50 in each tier, called 150 pokes garbage, and say 30 BL of various kinds of pokes, then that's only 530 pokes that either have a place or have no place.. at this rate that leaves around about 200 spare pokemon that are probably at some standard able to form an interesting metagame with other pokemon.. some pokemon like plusle and corsola (see: garbage) would end up being in a really low tier with tons of LC and Middle Cup mons, should we take it to extremes, but it seems that a lot of pokemon people would like to use don't have a tier in which they're really valid (see, for an example that suits me, mawile gen 3-5, it was sh*te even in NU, with both poor bulk and attacking power).. NU is always over-full, but an official PU at this rate looks like it could be valid. They say at the start of a gen that the UU looks like the previous gen's OU to an extent, and we're seeing large elements of truth in it. So surely it is not a stretch of analogy to wonder where last gen's NU pokemon go? Or even DPP/HGSS? Maybe we could even have 5 stat-based tiers + ubers (+LC and LC UU)? I'm just thinking with the absolute weight of pokemon we have, why some of them still have absolutely no niche and look like they never will be, and also looking at some pokes in prvious gen's NUs that look like they have something to offer.. I can see that in some ways, madness lies, but I think at the same time we've an overwhelming number of pokemon we can use.. I've even beeen toying with the idea of creating a tier from the bottom up, with magikarp, feebas, wurmple, etc. and working out what outclasses stuff in there, and removing stuff until I have the lowest of low tiers.. but that's a fun story I should probably keep to myself.
tl;dr - I support the idea of an Official PU, especially under the sheer weight of pokemon we have.
Lol here's another weird thought - a tier like monotype except it's mono-egg group or mono-shape or something like that...
I guess I'm being a tierwhore but I still think we have shedloads of pokemon and not enough desire to see what each one was built to do.