Which country's players have the heaviest average weights?
heaviest average weights refers to MAX(AVG(weight))
SELECT t1.name FROM Country AS t1 INNER JOIN Match AS t2 ON t1.id = t2.country_id INNER JOIN Player AS t3 ON t2.home_player_1 = t3.player_api_id GROUP BY t1.name ORDER BY AVG(t3.weight) DESC LIMIT 1