Metal toys can touch each other, with the only risk being something getting scratched.
Glass toys can touch each other, with the only risk being a scratch or chip if they're jostled and clink together hard enough.
Wood toys can touch each other, again there's scratch risk, but nothing chemical.
Pure silicone toys can touch each other with complete safety, the only issue then becoming shared lint.
Hard plastic toys can touch each other with no consequences whatsoever, just like any other household plastic.
The things that actually can't touch each other, and which also can't touch pure silicone, are: silicone composites, TPR, TPE, PVC, rubber, latex, skinlike materials, and most infamously jelly. Various combinations of those can cause chemical reactions with each other and melt into each other. They can also damage pure silicone. A jelly rebbit can even melt itself, if the clitoral attachment rests against the shaft.
Regardless of toy types, it's a pretty good idea to keep each one in its own pouch, to prevent chemical melting, to keep things from getting scratched, to keep things clean and lint-free, and to prevent spreading any germs if something accidentally gets put away without a thorough cleaning. Pouches don't need to be expensive. You can use sandwich bags, old socks, cosmetics bags, wine bags, or bags designed specifically for toys. It's best to use padded bags for glass and wood, lint free bags for silicone, and bags that seal tightly for skinlike toys that need to be stored with corn starch.