An alliance has many ways of saying it (truce, team, peace, or simply ally) and it is against most personal rules and is very unsportsmanlike. Not only will you will get banned by just about every player in every game, but you will also get called
(insert rude name-calling) and just about everything else in the book of offensive names, so don't do it! Instead do the skillful tactic of creating a neutral border which is not allying regardless of what others say. If confronted I always use the phrase "One enemy at a time." It truly is an art to seem as harmless as possible so the enemy goes the other way, but remember: "you are still enemies!" If he ever makes it too easy and it would benefit you to attack, then you always should.
The process usually goes like this, but varies from map to map.
Sometimes players will keep the top neutral for as long as possible but will fight each other at the bottom.
I hope this helps because I'm tired of seeing players ask others players to ally, especially when it involves players over the 20 rank mark. This is a special post written because of
(insert douche's name) who truly is an asshole for ruining a game that specifically said "no ally, no teams"
There are many others out there like him and you know who you are, stop being little shits and grow some balls, Good luck!
Edit: To better suit the thread.