When they're edge grabbing-and ledge invincibility has run out-and you're on the other side of the stage, throw out a PK Freeze. Some players will instinctively jump up to avoid it hitting them. Consequently, they will jump right into the path of the PK Freeze. This doesn't work against all players, but I've pulled this off enough times to know it's a viable tactic.
PK Freeze is a pressure move more than anything else. It makes the opponent feel like you're right in their face even when you two are on oppisite sides of the stage. It's this sort of pressure that makes opponents play poorly.
Also, it makes for a good spacing game too. When you knock them away with a Jab Combo, fire off a PK Freeze if it sends them far enough away. Sure, they may airdodge or shield it, but most players won't be able to think about approaching because-holy-****-there's-a-giant-snowflake-coming-at-me-I-must-avoid-it.
You will rarely hit with PK Freeze. At most, I'll land it twice per match, usually once. But it's not supposed to hit. If used smartly, you should never be punished out of a PK Freeze.
Well, hope that helps your PKFreeze game a bit. It's a really underrated move, but I myself use it quite a bit. It almost always misses, yes, but I'm almost never punished when I use it, because I use it in "safe" situations.