If you need a special tool, you are probably doing it wrong.
Originally the whole point of using a link is so you can service the chain without a chain tool, and there was no need to carry a chain breaker in the field because you could carry a spare link or two to repair a chain if needed. They could also make more money selling (one time use) links than tools - so it was a win win.
Marketing guys have now worked out they can now make more money by selling special tools for the special links that don't need a special tool.
I would invest in a chain breaker and not use links if you need a tool to undo the link.
As far as getting links undone - they do need to clean and free of grit. Press the plates together with figures, and push the link pins towards each other. It will open easily with virtually no pressure. If you need to apply pressure, wiggle it around, till it pops open. If it won't release in 30 seconds, clean it some more.
Sometimes the link is damaged or faulty, and won't easily open. In this case there various techniques (Pliers, point pliers, loop of wire around link pins and twist till they pop.) which may damage the link, but if you can't open with figures, its stuffed anyway, so go ahead with brute force and replace it.