I'm a scheduled tribe candidate. I have no distinctions on my CV. Should I stay in IIM Ahmedabad or should I go to IIM Indore for lesser competition?

You should stay in IIM Ahmedabad. Discussed below are the reasons why.

Comparison: (Winning Institution - IIM Ahmedabad)

• You will face the same level of stress and workload at both IIM Indore and Ahmedabad. But the placements at IIM Indore may not be as good as those at IIM A. You definitely stand a better chance of a good job at IIM A. 
• Also, in terms of brand value and ranking, IIM Ahmedabad is significantly ahead of IIM Indore which would further add value to your CV. 

Useful Tips:

• You can turn the competition to your advantage by making friends with smart and positive people and getting into their groups for project work. 
• Be diligent in class. Remember, there is no option to hard work. 
• Work on your communication skills if they are weak. Actively participate in co-curricular and extracurricular activities. 

IIM Indore has a big batch size as compared to IIM Ahmedabad. If you want less competition then stick with IIM Ahmedabad. Following this would help you carve your own way amidst the competition around.

Trust me, the experience is definitely worth it. You wouldn’t regret being a part of the IIM A fraternity.