Oracle offers three ATG certifications.
1. Oracle ATG Web Commerce PreSales Specialist.
2. Oracle ATG Web Commerce Sales Specialist.
3. Oracle ATG Web Commerce Suite 10 Implementation Developer Certified Implementation Specialist. (1Z0-510)
ATG Pre-Sale and Sale certifications are online and made available only through partner network. Third one is developer certification and you can take it from any Oracle authorized examination centers like Pearson. This post is about developer certification.
ATG Developer Certification
You can find more details about the developer examination from here.
Oracle made available enough documentation for ATG. However there is no specific documentation which covers only the developer certification topics. You might have to read multiple documentations to prepare yourself for the examination. I would suggest you to go thru following documentations.
According to me the guided learning path presentations are more than enough to pass the developer certification examination. However those presentations are made available only in partner network. The first six chapters in the repository guide should be good enough to get more than 80% of the repository related questions. On the commerce side you need to focus on using & extending product catalog, all chapters related to pricing and promotions, inventory framework, abandoned order service, order fulfillment, order approval process (B2B). I have seen very few questions related to page development. Also it would be good if you can open up ACC/BCC and do click thru to get familiarized with features in ACC/BCC.
Another option available for developer certification is ‘Oracle ATG Boot Camp’. You can find more details about the boot camp here.
You can find few sample questions at Oracle site.