A19 is a toughie. So the level starts like this:-
It *looks* easy but those two vertical teleports are a very clever trap. Something falling through the left teleport cannot easily get across to the right side of the screen and vice versa for the left. In fact the only way to finish the level is to get both shapes onto the same side of the screen *before* starting to kill anything, as the only way to get something on the right over to the left is with the assistance of one of the other blocks.
That can be hard to visualise, so if you still need help here's what I'm talking about in 'hint moves'. If you pull those 2 rightmost blocks down like this:-
you have the option of pulling either the skull or the pacman down through the right teleport. But pulling the skull down doesn't really help, you still can't get it over to the left, and pulling the pacman down will kill the 2 pacmen but make it impossible to kill the skulls.
I think this is where you're getting stuck, as you're not seeing the third option here. You can now pull the *other* pacman down to the right:-
This solves 2 problems.
1. It puts both pacmen on the same side of the level, making them easy to kill
and
2. It makes a ledge that the rightmost skull can drop onto, making it easy to get it over to the left.
That's the hard part of this level, realising that the 2nd set of blocks must be on the same side of the level *before* killing the first set of blocks.
I hope that's enough of a hint for you, but if you're still stuck message me here again and I'll send you a full walkthrough privately :-)