as far as I know, Deloitte will require you to take 2 online reasoning tests, namely, Numerical Test and Verbal Reasoning Test. These are administered by Kenexa (formerly PSL). The Kenexa format is commonly used in investment banking and also in the consulting industry.
The Numerical Test consists of 20 questions with 20 minute time limit. You can go back and forth and change the answers (but don’t do it). The level of difficulty varies and proper preparation using tutorials is a must! The best place to learn how to get a top score is probably GraduateMonkey (just google the name). You will need to look for a Kenexa type tutorial they have.
The Verbal Reasoning Test consists of 24 questions to be answered in 18 minutes. The key is to read the questions very quickly FIRST then look for answers in the paragraphs. You will still need a lot of practice and proper tutorial. Assessmentday practice tests should be good to practice.