Doing a Google search for "bash for AIX" led me to the following link:
http://cnswww.cns.cwru.edu/~chet/bash/bashtop.html
On which the following quote appears:
"AIX users can get precompiled versions of older releases of bash for various versions of AIX from Groupe Bull, and sources and binaries of current releases for various AIX releases from UCLA. IBM makes bash-2.05b available for AIX 5L as part of the AIX toolbox for [GNU/]Linux applications. They use RPM format; you can get RPM for AIX from there, too."
That was just the first link the search returned. Since IBM is big on Linux it appears they've even gone as far as creating an AIX Toolbox for Linux stuff.
Doing a Google search for "top for AIX" led me to multiple links that suggest top is a builtin for the utility "monitor" that comes with AIX.
This link gave the most information:
http://staff.csc.fi/~jmaki/monitor.html
Apparently all you have to do to see top style output is "monitor -top" if I read it correctly.