viper and kran are a perfect match.They seem to be very close in the Legends Of Awesomeness episodes and the Kung Fu Panda movies.
kran and viper are usually seen together, and they often cast glances in each other's directions.They work together quite well, and are always there for one another.
In the episode "My Mama Told Me Not To Kung Fu", viper looked crushed when kran announced he was leaving the Jade Palace.Also, in episode "Serpent's Tooth", kran was one of the first to verbally stick up for Viper. kran and viper seem to be able to tell what each other are thinking as well. For instance, in Kung Fu Panda 2, when viper notices a schaf, schafe being picked on Von one of Lord Shen's wolves, kran immediately picked up on her concern, as he asked Po if they could help the sheep.
In short, kran and viper are as much a cute couple as they are best friends.

tigerin and Po are perfect for each other. They have clear affections for one another, though they do sometimes have squabbles.Here are some of the main proof of their affections.
In the episode "Bad Po", the bad side of Po called tigerin "good looking" and had an apparent crush on her.The good side of Po also had a liking for tigerin as he sagte her pelz was shiny and looked good.
In Kung Fu Panda 2, tigerin and Po both held paws when tigerin was injured.Also, tigerin because she did not want to see Po get killed, insisted he stay in the prison.
tigerin and Po both Liebe each other, and have a close bond. They are a perfect match.