OK, I'd like to address abilities that were newly suggested.
The main group of abilities I'd like to address are (again) stat-altering abilities. Fuzznip has indicated on IRC that he may disallow Bulk Up from movepool submissions, despite it being a Type-Move requirement (yes, he can do that). While this may initially seem to discredit my warnings against stat-altering abilities, when you look at the rationale behind this consideration, you'll see that the arguments for these abilities are actually worse off! Plus, I have a sort of desire to have Bulk Up kept in the movepool.
The big thing, of course, is the resultant physical power of CAP 11. With 252 Atk Adamant, a CAP 11 with a +1 or equivalent boost deals 56% - 66.5% to 252/176 Skarmory with Close Combat. That's a guaranteed 2HKO accounting for Leftovers and ignoring Stealth Rock. 252/268 Hippowdon and Crocune suffer 51.4% - 60.7% and 50.7% - 60.1% respectively, a guaranteed 2HKO with SR+Leftovers on both counts. Against these threats, a +0 CAP 11 can win only with good prediction, but it's clear that a +1 CAP 11 requires minimal prediction, if any at all, to win the same battle (through either hitting the opponent on the switch or Taunting it). Togekiss certainly doesn't need these threats out of commission; weakening them would be enough. For this reason, I strictly oppose Clear Body, Guts and Intimidate off the bat. In the interests of keeping Bulk Up not broken (the justification would be that it spends a turn setting up), I am also extremely wary of Quick Feet, and I cannot support it. Similarly, Soundproof and Suction Cups I must reject as well, because immunity to phazing is overkill and redundant with Taunt. This also means that I can't support Adaptability anymore.
Now for the others:
Normalize: This is just so situational, man. Normalize robs CAP 11 of its STAB, in exchange for possibly relying on its defenses, which aren't that good, while it attempts to paralyze non-Ghosts. Maybe MAYBE for flavour, but not competitively. no
Serene Grace: I've already expressed multiple times why I don't like hax abilities like this one. no
Skill Link: I believe that Volt Absorb deals with many of the tangible Substitute strategies just fine, and Skill Link won't help much against the other ones (Breloom). There's a reason Deck Knight suggested this as flavour. no
Synchronize: I've said this before, but it's so ironic how this ability doesn't properly combat Togekiss's biggest threats at all. A lot of the less defensive threats have Thunder Wave as merely a tantalizing option. no
So really, the only remotely viable options I'm seeing are still Thick Fat and Immunity. It's unfortunate because I'm mainly doing this to suggest poll options for Fuzznip and he needs three options other than No Secondary Ability.