In 2016, Mary joined the Marble League as part of Team Primary, further competing with the team in Marble League 2017. In Marble League 2018, Mary and her brother Prim participated as a part of Team Momary, along with Mo and Momo.
In 2018, after rejoining Team Primary, Mary participated in the Amazing Maze Marble Race, placing 10th.
Mary, along with the rest of Team Primary, failed to qualify for Marble League 2019, and as such participated in the Marble League Showdown 2019. Team Primary placed fourth, qualifying for the Marble League 2020 Qualifiers with 36 points overall.
Mary and Prim were sent as representatives for Team Primary for the Marbula One 2020 season. Mary performed very poorly, failing to score a single point for the season. Because of this, she has become a meme among the fans, with many comparing her to a cube.
|Marble League 2016||Balancing||Team||15th||208 cm||0|
|Relay Race||Team||13th||24.60 sec.||1|
|Collision||Team||3rd||Consolation Round Winners||5|
|Sand Rally||Individual||9th||58.58 sec.||0|
|Team Pursuit||Team||12th||26.17 sec.||0|
|Precision Slalom||Team||15th||7 pts||0|
|Quartet Diving||Team||12th||28.69 pts||0|
|Marble League 2017 Qualifiers||Relay Race||Team||2nd||9.92 sec.||12|
|Block Pushing||Team||3rd||65.6 cm||10|
|Marble League 2017||Funnel Race||Individual||1st||1:44.51||25|
|Fidget Spinner Collision||Team||3rd||3rd Place Winners||15|
|Block Pushing||Team||14th||124.0 cm||2|
|High Jump||Individual||12th||36 cm||4|
|Marble League 2018 Qualifiers||Curling||Team||1st||Winners||8|
|5 Meter Ice Dash||Individual||5th||5.02 sec.||4|
|Marble League 2018||Team Pursuit||Team||8th||32.20 sec.||8|
|Snowboard Cross||Individual||13th||53.90 sec.||5|
|Ice Hockey||Team||8th||Quarterfinal Loss||8|
|Amazing Maze Marble Race 2018||Maze||Team||10th||Heat Loss||-|
|Marble League 2019 Qualifiers||Block Pushing||Team||16th||91.5 cm||3|
|Marble League Showdown 2019||Collision||Team||4th||3rd Place Losers||9|
|Marbula One Season 1||O'raceway Grand Prix||Individual||15th||5:35.71||0|
|Hivedrive Grand Prix||Individual||16th||+1 lap||0|
|Greenstone Grand Prix||Individual||16th||6:14.61||0|
|Razzway Grand Prix||Individual||16th||5:44.81||0|