Rank gap in ranked matches

Hi there guys,

My friend recently started playing and I’d like to know how we could play together, even with a rank gap. I tried to search for some info on this but unfortunately I couldn’t find any…

E.g. Can a Bronze play with a Platinum? Can a Gold play with a Master? Can a Diamond play with a PunkMaster?

I remember I saw something about 5-stack on higher ranks, but since I usually play solo I never had any interest in that.

Thanks in advance.