AP carries as Supports
Disclaimer: I am only B5. My opinions are basically worthless, but I'm still gonna give them.
I have noticed lots of arguing about wether or not taking an ap carry bot lane as "support" is a good thing for the team. I think that sometimes, this can be a good thing, depending on several factors:
The Specific Champion: Some ap carries have a kit mostly based around damage, such as
or
or
. These champs are pretty much useless unless they have massive amounts of ap, and can do the Deleting dance. I feel that these champs are rather sucky as supports, since they count on being fed, and leave the adc in a pile of sadness.
However, some ap carries, such as
or
or, to a leser extent,
, have a kit with a lot of cc or control. These carries, while they enjoy being fed, can survive just fine on less gold, and help take some of the damage dealing away from the adc (that saying, the best cc is death, can be carried over to, the second best cc is knocking out half their health). I have semi-carried quite a few bronzie games as support
, either by feeding my adc, or getting fed myself.
The Team Comp: Sometimes, in my Bronzie games, I will discover myself in a situation where my entire team is ad based. This is bad, since the enemy can just stack armor, and be fine. In this case, a true support champ, building ap, wont do a whole lot. However, a support
, building cd and ap, can burn through the enemy ranks (pun intended) quite easily; and if the enemy builds a wee bit of mr to counter the "support" annie, they would have to sacrifice some armor, allowing your other allies to do more damage.
Being in Bronze: I'm not sure about the rest of you diamond/gold/master/whatever players, but sometimes, I get an adc who might not be playing to the best of their abilities. For example, recently I had a Lucian, who enjoyed sitting under turret and doing nothing. Not farming, not fighting, not anything. I believe he got lvl 6 as I was lvl 10 (I was his "support"). When I get an adc who doesn't play right, I have to pick up the slack for him, which is difficult with a Blitcrank.
Also, In my games, and probably Y'alls too, I generally have a lane that will feed it's butt off. I have to compensate for that.
For the TL:DR, there are certain AP carries with built in utility that can be ap supports. There are also situations when your team lacks ap, and you can forcd the enemy to split their defenses between ad/ap by building ap. Also, in a lot of lower elos, and maybe some higher ones too, there are some adc's that are a bit edgy in their skill level, and the support has to pick up the slack. Spoonfeeding ftw!

(usually doesn't go well) and


"Support", get fed and tell everyone she works!
)
. Right question is not "is that good for a team" because everybody knows this can go well, it's "why conventional supports are so weak they can be so easily replaced"?
)
, Q and R can be used for some sick secures, provided you don't accidentally steal the kills
as middle ground "safe" AP Supports. They will always deal significant amounts of damage if you build for it and they will always have utility to protect a carry. You can build them traditionally or AP.