Pikachu QAC has potential for running away imo. The dilemma with using it to approach is that he doesn't have a great hitbox while using the move, and you're limited in ways to beat shielding/walls. Frankly, you would be trying to throw the person off instead of gaining a viable new tool. It's much more of a trick than a new grab/high priority attack/actual mixup.
For running away however, since it's a mobility tool basically and you don't have to worry that much about the other person's hitboxes if they can't reach you, I could see him being annoying to catch or corner. I'm not impressed with the possible applications as far as offense goes, and I think you'll be hard pressed to find legit scenarios where it works better than a traditional approach. Pikachu doing a running SH, or staying on the ground with the possibility of transitioning to SH, is a lot better.
The basic way I see it, is that if the other character has a solid wall or Sex Kick, you aren't going to beat that anytime soon with a QAC approach, and they could do it in response to seeing you QA/QAC with little regard. If you approached with it, you got swatted. If not, you lose space potentially. The second drawback not being a big issue (usually) if you're running away with it though. As far as Pika viability goes, he needs more damn range. He has some of the makings of greatness, besides that one huge flaw. I can't put him in god tier based off unforseen or hyped QAC applications.