Forum:Gladiator Beasts and Goyo Guardian

Hello.

I, for the life of me, could not figure this one out during a duel w/ my friend yesterday night.

Which is this:

I attacked his Gladiator Beast with my Goyo Guardian, which after it goes to the Graveyard, gets summoned to my side of the field. What we couldn't figure out is would he still be able to return his Gladiator Beast monsters that I destroy and place on my side of the field back to his deck at the end of my Battle Phase, or would it stay on my field and not be able to be activated due to it being on my side of the field and no longer in his control or graveyard?

Please, I need an answer from someone who TRULY knows the rules inside-and-out, as I have been playing the game since the beginning and know the rules quite thoroughly, yet I wasn't 100% sure on this one.. Though, my gut said that it wouldn't activate due to it being on my side of the field and in my control.

Thank you in advance,

Kevin