I used to watch a cartoon/anime style TV show when I was younger and I can't remember the name. It was animated like an action series like He-Man or Dragon Ball, but it had teenagers as protagonists. I remember that one of them could summon, from a pendant, a blue mammal (I say mammal cause I don't remember) possibly a tiger/lion, and they where like imaginary or from another dimension. I think the title was like a play on word for "Imaginary".
Sorry for being so vague about it, but I don't remember much and Google hasn't been useful either.