For shapeshifting I've just gone full Animorphs style, showing the progression in one panel. Then once it's established, you can just cut to them changed. The number of "steps" used in the transformation sequence could show how fast it is. If it's near instantaneous, just one transition between. If it's slower, have 5 or 6. I did a slower one here and here.
For teleportation, perhaps look at characters like Nightcrawler, and how it's been done in comics before.