Is it possible to monitor Oracle 10G using a third party monitoring tool? If yes what oracle agent should I use?
Answering the first part of the question, yes, you can.
Answering the second part of it, it depends on the product e.g. if you have Tivoli then you should use "Oracle Management Connector for IBM Tivoli Enterprise Console"
Disclaimer: Advice is provided to the best of my knowledge but no implicit or explicit warranties are provided. Since the advisor explicitly encourages testing any and all suggestions on a test non-production environment advisor should not held liable or responsible for any actions taken based on the given advice.