Firstly, Enough might mean just enough level to scrape off a okish score in JEE Advanced or it might mean good enough to score 90% in JEE Advanced. Going by my personal experience, you can clear INPHO (Indian Physics Olympiad) if your concepts of physics are strong enough and you can apply them practically. So, in a word, yes. JEE level physics can get you through, however syllabus completion and a large exposure to tough problems is a must.
See, I missed the cutoff for the camp by just 1 mark, and that was because my syllabus of JEE was incomplete. Questions worth 15–20 marks had come from those parts that i had not covered till then. Needless to say, my basics helped me reach that close to the cutoff. After my syllabus completion however, i reattempted the paper before JEE to see my level and, you know what? I scored about 98% then. Note that i had never ever seen the solutions of the InPhO papers, or even heard the methodology. So, yes… JEE Physics is sufficient. However, just one advice to you. Do not make the mistake that i made i.e. syllabus completion was not done in time. That hurts a lot.
If you have completed JEE syllabus before InPhO, then just practice from Irodov/Krotov/Gnadig a bit and you will be through to camps for sure. Just go to camps, and see for yourself what happens there. Best you do not know till you reach there. Just know that it is an awesome experience, according to my friends who made it.
All the best,