I don't understand all the calls to remove pokemon from the viability rankings altogether. This makes utterly no sense whatsoever, as you can use any single pokemon you would like to in OU, and we have the lower ranks of C and D for a reason. While I am not suggesting that we rank the likes of sunkern and pachirisu, I see no reason that pokemon like Salamence, Donphan, and Rotom-C should not be included in the list. Yes they are outclassed, but that is the purpose of the list, to show people that these pokemon are deserving of C and D rankings, and that's why C and D rankings exist. Pokemon being in UU is not a valid reason to remove it from the list either, as we have clearly seen in this generation pokemon such as Terrakion, Keldeo, Landorus-I, Latias, and Celebi, that were all at one point in UU or BL, and some still are, and this in no way makes them not viable in OU. Gen V also shows this exceedingly well, as pokemon all the way in NU such as Stoutland, Victreebel, Sawsbuck were all used in OU to great success as weather sweepers, and of course the case of scolipede in gen V who was a viable offensive spiker in every tier and notable in OU for being the best counter-lead to Deo-D when it was legal, despite being in NU. Eliminating pokemon from the list designed to show a pokemon's viability just because it is outclassed or the list is too large is absurd.
Still, things like Moltres: what nice does it have left in OU? Or Rotom-C, who has an added opportunity cost? And even if we don't remove things entirely, can't a lot of stuff in C go into D? And Liepard, who could possibly be used a suicide lead (Fake Out to break opposing leads' sashes, Prankster Taunt, Copy Cat to use the opponent's own rocks/spikes, Rain Dance for rain teams,) Swagplayer (as dumb as that is,) paralysis spreader, knock off, u-turn, trickscarf: it was ranked awhile back, but got removed. It's usable in OU, it can do stuff nothing else can, should it get added back (honest question, I actually do think it has more merit than Moltres)?
This list should be a source of information first and foremost, and removing pokemon from the list diminishes it's ability to relay information to new players who genuinely do not know whether a salamence is better than a dragonite or not because their only experience comes from in-game. This list should be acting as guide to new players, to make that learning curve a little easier to overcome.
Honestly I don't think new players will be looking at lower ranks much, and if they are it's a list of "things not to use because they are 'bad'" to them. And a lot of that stuff is niche, it's only going to be used on certain teams or when it's the only thing that can "fill in the gaps" for your team, said gaps not the easiest thing to find for newer players. The previously discussed Kabutops is C, but it's a fearsome swift swimmer and a top choice for rain teams. When a new player sees "Kabutops is a C pokemon," what exactly does that mean to them? Or Scolipede in B; why is it in B? It's not strictly outclassed by anything in S or A, why do "top players" think it's only B? What new player really scrolls all the way down to C, sees Escavalier and thinks "gosh, totally perfect for my team?" (not saying Escavalier is bad, I think he's great.)
If new players are really interested in getting into Pokemon, they should be reading analyses, articles, other threads, watching replays; the viability ranks should only be very rough starting point, and sticking anything with some sort of niche in OU is just not the best idea to me. If we strictly go by D's definition of "small niche in OU, more trouble than their worth," D would be filled with lots and lots of stuff that (sane) new or experienced players would never consider using on a team, and they'd only be there to say "never use these pokemon." Not being listed is just as effective.