Colleges in Tiruchirappalli

NIT Trichy, of course. It is one the best NITs across the country and the placements are also fabulous.
Plus, you'll get better exposure and culture there.
All the best.

Admission is through counseling based on the rank obtained in Tamil Nadu Common Entrance Test (TANCET). Hence, the only way to get a seat in J.J. College of Engineering and Technology for MCA is through management quota seat.
Details:
https://www.shiksha.com/it-software/course/master-of-computer-applications-j-j-college-of-engineering-and-technology-tiruchirappalli-16157

You will most probably get a seat in NIT Trichy through your ST rank.
Check last year's closing ranks here: https://josaa.nic.in/result/result/openingclosingrank.aspx

Last year, the closing rank for Other State Quota for NIT Trichy ECE was 731. So you might have a slim chance. You might get other branches in NIT Trichy.

CSE and ECE in NITT are pretty good. NIT Trichy is top among the NITs and placements for CSE and ECE are great here. So you should consider NIT Trichy.

NIT, Trichy is one of the best institutes for CSE. It is top among the NITs and placements for CSE are pretty good here. The only issue you might have is of adjusting to the new environment. Also, Delhi is much better to live than Trichy. So take your decision considering all the facts.

Elective in Industrial Robotics is available but not in Pure Robotics in Mechanical department.

You won't get a seat in EEE but you can get in production, civil, chemical, metallurgy and ICE departments.

You will mostly get a seat in NIT, Trichy with your ST rank.
Check last year's closing ranks here: https://josaa.nic.in/result/result/openingclosingrank.aspx.