Hello there!
One question, I was wondering can a Lion (large) grab a target while mounted? I assume it would be at least difficult for the rider to hit the grappeled target, but doesn't the mount need all his paw's to hold the knight ridding it?
Hmm, I can't find anything in the rules about this. So let me know what you think!
I would think as long as the lion had a light load with the rider, it could use it's improved grab ability, but the rider would most definitely need to make a Ride skill check to remain mounted - probably DC 15 to 20. There's no exact ruleset for it, so I'll assume it'll be up to the DM's discretion.