To add on, you can check the 'Teaming' rule on the rules page:
https://www.cubecraft.net/rules
Teaming is defined as intentionally working together with an enemy player in a solo mode game. Crossteaming is defined as intentionally working together with an enemy player in a team mode game. Both teaming and crossteaming are strictly prohibited in games with both solo and team modes available, as well as solo featured games.
Featured games will host solo games such as Survival Games, but as there will be a team Survival Games hosted in the future, teaming is not allowed in the solo version.
Teaming is allowed in FFA, Minerware and Assassinations.
Teaming is allowed when every remaining player alive in a game agrees to it.
As you can see, it says that teaming is allowed in FFA.