Riddle 1: The answer is a candle, which can be found in the Victory Dogs' Hideout.
Riddle 2: If you ask Alex for a hint, he will tell you to ask Amalia for help. You can ask her for a hint or the answer, which is nails. You can then answer the riddle by talking to Alex again.
Riddle 3: What carries its home on its back in the rain? The answer is a snail.
Riddle 4: Something that has a mouth on its head and eats everything. The answer is a backpack.