If you're looking for anime similar to Koala's Goodbye Song, you might like these titles.
One day, Sandy's father, Prof. Brown, sends her a stuffed koala doll from one of his trips. Sandy discovers that, after rubbing the koala's nose, he comes alive. His name is Blinky and he is from the magical "down under" Koalawalla Land. They are soon joined by his little sister, Pinky. Adventures ensue in both Sandy's world and Koalawalla land. Among the characters met are two men after the "magical talking bear", a lizard that bounces back and forth from the magical realm and the real realm, and kangaroo police officers.
Penelope is a cute and lively young koala. Through her mischievous streak Penelope cunningly plans various ways to draw on the walls and furniture, or imagine a method that allows her to be noisy early in the morning. Along with her friends Aladin, Lily Rose, Cezarine and Strombouli, Penelope imagines what she wants to be when she grows up – that is, if she can decide! With new experiences each day from befriending the birds in her garden and celebrating her birthday to hunting for shapes around the house with twins Milo and Madeleine, Penelope lives every moment to the fullest. No matter what happens, every day is a new adventure for the blue koala – even if she is a little absent-minded.