i want to know if i am taking classes for CAT do i have to take seperate classes for exams like ibps/bank/po MAT etc.?

CAT being a tough exam compared to ibps/bank,po/MAT etc,do i have to take different classes for each exams or just taking classes for CAT is enough as it will cover everything for bank /po/ibps OR MAT ?and what is the difference between the topics covered in CAT and ibps/bank po or MAT.?