In general Bain does the SOVA. The exact test/format is going to depend on role, recruiting channel, timing etc. (these things change constantly).
Ultimately, they will tell you.
Also, ultimately the same skills are required (don't overcomplicate this)
First, learn to case. (You need to know the same business concepts, ways of thinking, etc.
Second, practice with real tests.
Allocate your 30 minutes just like you would a normal test - try to move quickly through questions and watch the clock!
Now, in terms of preparation.
The best way is to really find online tests / questions and practice. Regardless as to whether is a new or old test, the principles are mostly the same:
- Time management (need to think quick)
- Business knowledge/context (incl key formulas)
- Critical thinking (answers that are very similar to each other...clues "hidden" in the text)
- Ability to interpret data/charts
Think of it as a merge of a case and the GMAT/GRE.
You need to be clear on some key case-related and account formulas (margin, growth, breakeven, etc) as well as be good at critically understanding the question (including nuance to questions) and parsing through complicated text with a fair amount of distraction.
You'll also need to be good at chart/graph reading.
The (old) McKinsey PST, BCG Online Test, Bain SOVA test, etc. are all quite similar so leverage resources across all of them.