This is a copy of my guide to "Gathering of the saiyans!" , as it worked for "Gathering of the saiyans!" it should work for each achievement
Hi i add a precision. you can do it at 2 , i did it at 2 .
You need to create a lobby at 8 and invite your friend ( in team death match ) , your friend join the other team and the 6 slots empty will be filled by A.I's.
The A.I's are chosen at random.
Choose the character from a series you need and the one with the right team wins the game.
I know that this solution is not practical at all because you must have found the right combination.
The reason why I am giving this solution, i trying to finish this game in 2020 so find 6 players is not easy.
So if you can do this at 2 it will be better
Update : I add a point that seems important to mentioned. You can do this from 2 to 8 players. the simplest would be 8 sincerely. and put the option that the teams do not change.
When you go invite your friends / boosters, one will join the opposing team, the next your team, the next the opposing team ect
I haven't found a way to change teams or join a particular team once in the lobby.
So if you are 4 for example it will be 2vs2 with 2 AI on each side, it will be easier because you will just need 2 AI which you need instead of 3 but you have to find the partners.
the more players there are, the less A.i there will be and vice versa