I recall reporting this a long time ago... I set pets up for auto-battle and all but a few seem to decrease in energy at all. 

http://beastkeeper.com/pet/893
http://beastkeeper.com/pet/304805

I know their are others, but these two are examples of ones that just seem to never have any battles at all. I know that there are pets in the arena to fight that are in their level range... 

It just seems that sometimes the pets are stuck for a few days... And to be honest I'm not sure... 

Are we aware of any issues with the battling system? I'd be happy to provide more information if you'd like. 

Thank for reporting!  Yes, this is a very similar problem to the one that you reported once, but its cause was different. The glitch should be fixed now. Sorry for the inconvenience.

Thanks Angel :) Much appreciated.