Going to have to disagree with you about Butterfree, Frostweaver. Butterfree gets access not only to Sleep Powder but Stun Spore as well, thus letting it double up on the guaranteed status effects (Something which Yanma can't do and which makes a major difference in NB where the Sleep clause is standard). Also, Butterfree has some actual SDef so it can - unlike Yanma - actually take a hit from something, so they're not really equal.
Oh, and don't forget that many of the inferiors (such as Fearow) have their uses in the UU too. =P
UU divison should not exist to begin with -_-; If Pokemon is designed in its most ideal manner, everything competes in the OU category =x
Megayanma, newly introduced to DP, can far outstand Butterfree's defensive power... alright, Butterfree got base 80 sp.def but a base hp that's comparable with Deoxys FR? You know that you suck if your defensive stat is comparable with Deoxys FR O_o;
Eh, true that Butterfree is the only compound eye user that can double store AND is flying/bug... so not *totally* overshadow-ed, I suppose... of course in practice, we'll always exchange compound eyes for STAB sludge bomb on Venomoth with the better speed and all too (even if it's just so slightly)... poison and flying are around the same of a trade (resist focus punch vs resist earthquake, both are good). STAB Sludge bomb can be painful now that it's a sp.atk too...
Really in practice, I'll use Venomoth over Butterfree anyday :x Butterfree is a dead givaway that double powder is coming. Venomoth can be slightly more surprising with a slightly better movepool.
Super irrelevant note on butterfree, is that it can also "accurately" parafusion with a 85% supersonic XD;
(for Alter Ego: I mostly play choice band Yanma for the 100% success in surprise factor :x everyone switches a lum berry user or best scenario, sleep talk heracross into Yanma for a free HP Flying near OHKO =P If it's sleep talk Zapdos.. well... not like Butterfree can win this one either XP)