if multiple targets are hit with Pulse wave, they have the mystics ta, does the attacker get the feedback damage for each hit character?

No. Pulse wave ignores all game effects including team abilities.

"Most" game effects.. PW will not ignore peanut-sized or larger bases, colossal size, etc.

Pulse wave ignores game effects possessed or used by characters with a line of fire drawn to them.

Some game effects state they can't be ignored, such as a character's Size, and some game effects aren't ignored because they are being used by characters outside of the pulse wave area of effect, such as a character outside the area of effect perplexing up the defence of a character inside the area of effect.