The requirements is kinda difficult just to qualify for the contest or raffle if I am not mistakes. Though other agents who have more than 20
players can easily obtain the requirement but the other can't easily get the 20 friends.
What if we will add friends to the channel randomly? Will it be acceptable even if they will left the channel in the following days?
Those who are active in poker with many friends with similar interest in poker can get the required numbers but if you know people who are not your friends but are playing pokers then, you can ask or invite them but do not add them without their permission, although OP did not specify the rules they consider that you will add your friend with the interest to join, the worst that can happen to a group is getting members added without their permission, the group will be reported as spam group.