Where do the bottom 10-20 percent scorers in a batch at IIM-Ahmedabad generally end up in life?

Your grades do impact the campus placement. Most of the finance and consultant companies will be out of bound if you do not maintain a certain CGPA. So, your choice is limited to the startups, media companies, tier 2 marketing, or companies that hire for character.

Once you start working, if you are willing to hustle and can communicate well, then you will be able to recover lost ground easily. And who knows, the startup that no one wanted to associate with might become the next big thing in the industry.

So, there is no generic rule here. As some of the students, who are in the bottom 20% do bad, some do average, and some make it big. In contrast to the top 20%, where most of the students do well, and a small minority of students do bad. 

Overall, it depends upon you how you perform in the real world as some top students also do struggle whereas some of the bottom students shine.