Swapping Glitch?

Oookay. Extending my feelers to see if anyone has encountered this GBL issue. And before anyone says anything, I’m not complaining about any sort of skill-level - I’ve made it to rank 7, and don’t expect to get higher.

The past few games, I keep running into players that seem to be able to switch in more than once in that time frame, and seem to “heal” when switching their mon back in. For example, I just played a round where I had KO’d a Shiftry with my Skarmory (saw the fainting animation). They sent in a Bastiodon, so I sent in my Azu and was able to deal with it relatively easily. Then the Shiftry showed up again, with a solid 10% of its HP remaining. I took the L, because my Skarmory came back in and finished it - seemingly just leaving a Stunfisk only running ground moves, so we kept hitting each other for 50% and I still had 1 shield. However, when the Stunfisk is at about 1/2 HP, I fire off a Sky Attack at…Shiftry? Who again had about 10% of its HP. I’m positive it had been less than 12 seconds, but even so, I saw that Shiftry faint twice…

I know that “switching” is a viable technique, but I have NEVER seen it like this.