In regards to Togekiss, I think C-tier is a pretty good place for it to be.
"Reserved for Pokemon who can be effective given the right support, but either have crippling flaws that prevent them from consistently executing their strategy or are typically inferior to Pokemon in the above ranks."
It can attempt to fill the same para-flinching niche that Jirachi does with Body Slam, Air Slash, Roost, and a coverage move, but the latter takes the cake most of the time due to its resistances, lack of SR weakness, and the ability to set SR itself if desired. Nasty Plot Togekiss works really well in combination with Jirachi however, and it can break through most opponents if you can paralyse them in advance. This isn't too hard if you have something like Ferrothorn, Shuffler Dragonite or a Jirachi of your own in the wings. Unfortunately it's a little eclipsed by Tornadus-T if Drizzle is up, but Togekiss is somewhat better at staying in and sweeping through teams in the late game due to Roost, better standing bulk, and the excellent Nasty Plot.
If Togekiss got Serene Grace Hurricane, of course, then that would be another story... :p
Check out Slowmons: A new metagame where the slowest Pokémon moves first!