Allow me to expalin how I see the concept, and why I state that making CAP11 a sweeper will fail the concept.
Yes, CAP11 could benifit from Togekiss' presence as well, however, CAP11 is unlikly to be paired with Togekiss with CAP11 as the sweeper.
Why is this?
Firstly, if we're taking CAP11 down the offensive route, and Togekiss is it's partner, that would probobly relegate Togekiss to being a supporter, as it needs support to sweep itself.
In addittion, CAP11 would probobly take the route of being a Fighting or Ground type.
So, we have this sweeper CAP11, of a Ground or Fighting type, designed to work off Togekiss' support. What can Togekiss provide of real note?
Nasty Plot passing
Heal Bell
Thunder Wave
Wish
Firstly, not all of those will fit on a moveset. Bear this in mind.
If I wanted something to provide Paralysis support, I would choose Jirachi over Togekiss anyday, especially as Jirachi provides better Synergy with a Ground-typed CAP11, and roughly even with a Fighting-type. Jirachi has better stats, stronger and more reliable STAB Flinching move, and a typing that dosen't get mauled by SR.
If I wanted to pass Special Attack, then I'd use Celebi, and pass Calm Minds. Recover makes Celebi MUCH more likly to get the pass off, and it's higher bulk and speed make it even more likly. Not to mention, yet again, Celebi does far better than Togekiss when you look at a Ground-typed CAP11. Oh, and did I mention it has Heal Bell too? And Swords Dance, just to make it even less predictable, and allow CAP11 to abuse Earhtquake/Close Combat, which Togekiss cannot aid [Best it can aid is Earth Power and Aura Sphere/Focus Blast]
Let's not forget these pokemon are more unpredictble than Togekiss. Togekiss isn't really a threat without paralysis support, and if it's spreading it, it loses coverage/recovery/boosting. Celebi and Jirachi are threats in their own right.
Basically Togekiss is outclassed as a supporter, and if we attempt to make CAP11 rely on Togekiss' support, Togekiss' useage will NOT rise, simply beacause Celebi and Jirachi do the job much better.
This is why I feel CAP11 should be the supporter. This is why I feel giving CAP11 a good offensive STAB, and few resistances is a bad idea. This is why I always say, if we make CAP11 a sweeper, we'll fail the concept. This is why I'm against the Fighting and Ground types, and for the Steel type, because otherwise, people will want a sweeper... because Ground and Fighting are not exactly supporting/defensive types.
However, in all honesty, at this point, I'm fighting a battle that's probobly already lost...
Oh, and defeating Blissey is minor, as a Togekiss with Aura Sphere, Nasty Plot and Roost outstalls Blissey, sets up, and 2HKO's.