Lesnar has a lot true real wrestling experience and even the entertainment wrestling experience will help him some. He knows how to keep going through the pain. I'd think some of the submission holds would just be hard as hell to even put on Lesnar because of his size and damn near impossible to hold for long. I'm not a small guy but I have no doubt if I put him in a full Nelson he could just shrug and snap my arms like twigs.
Couture's best bet is to keep him up right as long as possible and to find one body part and pound on it. Like a knee. If you get on the ground with him with out him being weakened then you're going to have real problems controlling him. Though I'm sure Couture is so experienced that he doesn't even think about doing a submission hold but just does it and can change with the situation without any delay. Either way it should be a good fight.
Couture's best bet is to keep him up right as long as possible and to find one body part and pound on it. Like a knee. If you get on the ground with him with out him being weakened then you're going to have real problems controlling him. Though I'm sure Couture is so experienced that he doesn't even think about doing a submission hold but just does it and can change with the situation without any delay. Either way it should be a good fight.