Here's some places to get some costumes:
stadium:ladybug costume: go to the fire truck then climb the ladder there will be a ladybug press A to get the costume.
pool:eagle:jump on the right mushroom and you will land on a cloud go to the bottom of the cloud and press A and a feather will fall press A on the feather and get the eagle costume.
beach:starfish:go to the top right corner of the beach their will be a star fish press A on it and you will get the starfish costume.
lawn:apple:go to the tree at the lawn climb it you will automatically fall down then an apple will fall on your head onto the ground go pick it up to get the apple costume.
n the tennis day prelims or finals etc. go to where registration is and there is one cactus that looks diferent from the others press A on it and you get the cactus costume.
athetes village:leo costume:after the fist tournament go to the athetes village then go to the fountain to get the leo costume