Dodge bug

The invisible one in my experience, happens when the defender uses a charge move that would cause your Pokemon to faint, but faints before it finishes using it, so on your screen it looks like both fainted.

The "regular" one where your Pokemon keeps switching out and back in happens when you correctly dodge but the undodged damage is enough to make your Pokemon faint.

When you correctly dodge a charge move, you receive full damage. A second later it rolls back to the actual dodged damage but if you were nearly out of HP you're dead and it's over.

It's currently making glass cannons hard to justify the use of for me right now.

Yes, but it attacks at least every 2 seconds:
If Vaporeon uses Water Gun, it uses it every 2 seconds.
If Jolteon uses Volt Switch, it uses it every 4 seconds.
You can still use charge moves during the loop.

I know for me, whenever I go against any Pokemon with Hyper Beam or Hydro Pump and successfully dodge it will cause that Pokemon to be in a non-faint/alive state thus making me switch out Pokemon. However, once I go to health restore that pokemon is not dead but has the health of when I dodged.