On my database when i do this query:
SELECT * FROM users u LEFT JOIN usersToStrategy uts on uts.userID = u.userID LEFT JOIN strategy s on uts.stratID = s.st
I think you are looking for GROUP_CONCAT
SELECT userID, username, fName, GROUP_CONCAT(stratNames SEPARATOR ', ') AS strats FROM users u LEFT JOIN usersToStrategy uts on uts.userID = u.userID LEFT JOIN strategy s on uts.stratID = s.stratID GROUP BY userID, username, fName