How to connect an android phone with the basic phone having unlimited data packs . How to use the data on their phone in android using bluetooth?
If that basic mobile has the future of bluetooth hotspot, you can make use of that. Otherwise it can't be done as per your requirements.
If it does not have to be Bluetooth, but WiFi would make you happy as well: For quite a while now, Android offers a nice feature called Hotspot. The one with the unlimited mobile data starts that on his device, and everybody with WiFi capabilities can use it like any other WiFi hotspot – if they are told the connection data (WiFi password and hotspot name).
Try using bluetooth PAN (Personal Area Network). Some bluethooth adapters with third party drivers have excellent features to deploy and maintain a PAN. Internet sharing is possible over Bluetooth. You will need another PC to establish such a network. Both the basic and android phone will connect over bluetooth.
Use Easy Tether Pro. It enables an Android to share data connection through bluetooth with another Android.