By myths and origins do you mean the real life things that some of the various Pokémon are based on? If so then good targets for the report in regards to dragons would be Charizard, Dragonite and Gyarados. Gyarados covers the classic Chinese image of a dragon pretty well. As for the other two they semi-resemble the type of dragon you'd see in a traditional fantasy setting. There's also Vulpix/Ninetails and the Japanese myths regarding multi-tailed foxes or perhaps Lapras in possible connection to the Loch Ness Monster.
I'm sure there's plenty more but those are the best ones I can come up with off the top of my head. Good luck with the report. Let us know how it goes ^_~