When I was a silver 1 I wasn't able to play with my friend who was a silver elite master. So he switched his account to his silver elite account and we could play.
So you can play with a person that has 5 ranks higher than you, but not 6 or above.
There was an update in CS:GO, which introduced levels in the game, now what these levels are for is pretty much to restrict people from playing MM (MatchMaking) right from the get-go ( pretty much buying the game and playing MM) this way, it would reduce the ammount of "noobs" you would catch in MM, now, to play MM you need to have level 2.
How do you get level 2?
You play, Casual, Arms Race, DeathMatch, even some community servers provide XP, all you have to do is get level 2, this way they can at least "force" the player to know something about the game before playing MM.
When you first start playing you need 10 MM games before a rank is given to you, while you do not have this rank, unless you are in a full lobby (5 people, including you) you will not be able to play with ranks higher than MG1 (Master Guardian 1) the rank insignia is a single AK47.
Remember that if you play with your LEM (Legendary Eagle Master) and DMG (Distinguished Master Guardian) friends, you will have a hard time playing properly (unless you secretly are a csgo pro) since they will be high above your skill cap, which might cause your rank to inflate and make you lose a lot of upcoming games when you play solo, so i suggest, play alone your first 10 games, then play with your friends, after you get a rank.
To answer your question:
- You need level 2 to play MM (Level that you get playing Casual and Other games modes).
- You need 10 MM wins before you get a rank.
- Don't play with your High Rank friends, you will just drop down when you start playing alone and get de-motivated to continue playing (I know this from personal experience).
Best Answer
In a 5 man lobby you can have all ranks, in other cases only 5 ranks plus or minus.
If you have unranked players and the lobby is not full, the ranks you can play with are from Silver 1 up to Master Guardian 1. It's made to disable CS:GO boosting companies and smurfs to queue with low ranks while playing on high rank. For example unranked account can't queue with Supreme, in the past it was possible so you could play as Supreme against MG ranks because your friend was on Silver or unranked account with very low hidden ELO ;) It's not possible anymore.