FYI: Plastic will stick to both litho and paint over time, especially if exposed to temperature and humidity variations.
Also, tissue paper (even archival) will do the same thing.
Do not ever use bubble wrap for anything. The gasses released from inside the bubbles can do harm and the plastic will stick to paint and litho.
The following is what art museums use to store items.
Glassine
http://masterpak-usa.com/cat_201_glassine.htm
Archival quality Tyvek:
http://www.masterpak-usa.com/cat_206_tyveksoft.htm
(Yes, the same material as house insulation, but softer and without ink graphics.)
I have close friends in the art world who manage and ship museum collections. I have talked with them in depth about packing and shipping toy trains. Unfortunately, museum level packing techniques seem to be completely unknown to toy train collectors. When I go to York and see the high end dealers wrapping up early tinplate in newspaper it boggles my mind...
FYI: There are other new archival materials like Dartek clear plastic, but Tyvek or glassine may be easier and more cost effective.
Also, be aware that the toys will be effected by whatever you put in the box with them, like styrofoam peanuts or newspaper.
Cloth may sound like a good idea, but long term the toys will be exposed to whatever dyes or chemicals are in the cloth. Plus heat/humidity may make it stick just like paper.
Of course, conditions vary and exposure to materials depends upon how long they are in storage, heat, humidity, etc. Sometimes you can get lucky and wrap toys in newspaper, baby diapers or whatever and get away with it. But that one time the heat makes something stick to your 100 year old $1000 treasure...
Tyvek/glassine is a good investment as it can be reused.
Good luck,
Bert