>>42911159Considering they mentioned Togekiss in the same breath, it's almost definitely because of Serene Grace. That ability has allowed so much bullshit to take place, it's a hax enabler.
Jirachi in particular infamously exploits it. Like all the other mythicals of its ilk, it has 600 BST with an even distribution down the line. It has a movepool capable of doing many things, it has great bulk and just enough speed and offense to bloody your nose or worse. I used to run a mixed Jirachi that carried so much weight and allowed me to win battles I had no business ever winning, and the main reason for that is Serene Grace + Iron Head. That's a 60% flinch rate right there, enough lucky rolls could flinch you through shit that would otherwise completely destroy you. And frustrate your opponent to boot.
Also, being steel type makes it a huge bitch to get rid of in general. Even more so in gens before Ghost and Dark types were buffed.