Most of the time, the short and simple Ganon combo of Side Special followed by Down A is unavoidable. But sometimes, some fighters get into the invincibility frames before the Down A activates. Is it something any character can do? If not, are only certain characters immune (if so, which ones)?
You may be referring to how enemies can tech Flame Choke, in the same way they can do an intangible breakfall against any surface after being hit. It's a universal technique that any player can do, though it requires timing precise enough that you won't see everyone do it.
While teching Flame Choke will indeed mess up your next hit, if you can predict where the opponent is going, you can get there first with a dash attack or forward tilt.