It was definately animated, though if it was anime I can't recall. There was a young boy stuck on an alien planet with just a sort of large communicator, a bit like a ball, which he carried around with him. He used this to talk to a group of people somewhere else. There was a woman, and old man and the bad younger man and there might have been more. They'd all take turns in giving the boy conversation and instructions.
At one point the bad young man tried to get the boy to swim in a lake, but the woman stopped him before he could. Which was fortunate because late in the movie the boy does go back to the lake and it's full of monsters or something. That was near the end though.
The boy make friends with a strange animal which he rides around, and he rides into a cave that's full of some kind of tentacle monster which eats the alien creature and steals his communicator. The boy barely escapes, but now he is alone. The old man dies and they shoot his body into space with the other cummunicator.
At some point the bad young man is carried to a place by some kind of flying puppets where there's an evil entity. He sacrifices himself to the entity for some reason which proves he wasn't so bad after all because it kills the entity and frees the puppets. Also I remember there being water lillies on a lake that gave birth to small fluffy creatures, some of which got stuck and were saved by the good lady I think.
In the end the boy gets hurt by the lake monsters and is rescued by a passing space ship.
Does any of this sound even the tiniest bit familiar to anyone at all?