Here is the full list of all 40 Summer Catchers achievements.
Complete tutorial
Buy all outfits, cars and postcards
Activate a secret code
Find all stashes (co-op only)
Listen to the whole inventory song
Receive the Bell
Catch the World Map
Find the Casette Player
Bucket the Meteorite
Reveal the Crystal Skull
Find the Firework Rocket
Help musicians to put on a great show
Tame an owl
Tame a ferret
Tame a fox
Tame a goat
Tame a robot
Tame a chameleon
Tame all pets
Complete all mailings
Play in co-op
Overcome a hill or a bridge. No boosters, no bubbles
Chew some bubble gum (co-op only)
Break down a car before a race (co-op only)
Use a bell to wake up a sleepyhead
Leave a race right after a crash
Collect 1000 mushrooms from totems
Collect 1000 rainy mushrooms
Catch a bubble, a drum and a horn in one race
Overcome 5 obstacles in a raw in a bubble
Win the Jar with fireflies