Everyone starts with an ELO of 1000, so if you are playing with a boosting partner, you can get Rising Star and Overmind when going towards Grand Master. This achievement does not have to be ranked games, but since both Rising Star and Grand Master do require ranked, might as well do them all together.
The first person will beat the second person repeatedly until they have an ELO of 1200, unlocking Overmind and Grand Master. The second person will then start winning, unlocking Rising Star, and continuing to win until they have unlocked Overmind and Grand Master. The first player then will need to win one game, unlocking Rising Star.