Formal:
* The yoga guru led a peaceful meditation session.
* She consulted a financial guru for advice on investing.
* The marketing guru shared his insights on building a brand.
Informal:
* My friend is a baking guru; her cookies are legendary.
* He's a real gaming guru, able to beat any level with ease.
* I'm no tech guru, but I can usually figure out how to use a new app.
Figurative:
* He became a guru of sorts in our group, always offering solutions.
* The new restaurant was a culinary guru, creating innovative dishes.
Remember that "guru" can sometimes be seen as a bit of a buzzword or a title that can be used informally, so consider your audience and context when using it.