Ideas on how a third Kaiju can be added to GvsK without ruining the plot

Having Kong and Godzilla fight with a clear winner. Afterwords them fighting a third monster could possibly work, or one of the other monsters kills it before they fight. 

Doomsday was only a small factor in why BvS was a critical failure. There were many other bigger reasons. Doomsday could have worked but he wasn't executed well. If they don't make the same mistakes that film made, there shouldn't be a problem.