Obedience training is about 7 months behind schedule for this pup... but it's never too late to start!
I would ALWAYS recommend you listen to Hiraeth's advice! She's got loads of experience and great results to show for it.
My thoughts:
Danes, Corsos, Mastiffs and dogs of all flavors need to RESPECT their leaders. Respect is easily earned when your dog is a puppy and you provide it everything it needs.
Consistent rules help the dog grow into a confident, respectful companion.
Doing the whole dominance "take-down" might work in the right circumstances, but it also can easily create fear and disrespect in a dog... and that can go horribly wrong, in a heartbeat.
Dogs will test the rules occasionally, depending on the temperament of the individual - how you respond to the test will determine if they test them again later. Ignoring the testiness can be very effective when the dog is after attention. Ignoring a dog testing the rule of no-counter-surfing would not be very effective...
For brandon1234 and the Girlfriend's Corso... it sounds like the dog was allowed to grow up without rules, and that has resulted in a big puppy that likes to take control, thinks everything he sees is "his" and doesn't know how to respond when things don't go the way he wants them to. For the family, who spoils the dog and enjoys giving in, that looks fine (to them)... to anyone who thinks the dog should not be the one pawing on the human for attention... things can (and did) go horribly wrong.
9 months is still puppy. Still LOTS of room to build rules and a healthy relationship - BUT - the family the dog lives with will need to be involved.
I would put this puppy on NILF. Nothing In Life for Free. The puppy must WORK for every bite of food, every treat, every pet. And when given, the treats must not be taken away - unless you "trade up" with something else. You can practice that by giving an antler, asking the dog to "drop" it, and trading it for a bully stick, asking the dog to "drop" that, and then giving them a piece of deli meat or cheese (or other "top" reward). If you really want the dog to like you, after trading the bully stick for cheese, have them sit and LOOK at you (your face, not the treat in your hand)... and give the bully stick back... and then don't disturb the enjoyment of the bully stick.
We had a 'bully' of a rescue dog (bulldog/boxer mix). One of the BEST exercises we did with him was "look at me"... hold a treat in your hand and hold your hand out to your side... the dog will probably watch your hand. Say "look at me" and WAIT for the dog to look you in the eyes. The INSTANT he looks you in the eyes say "GOOD!" and give him the treat. Repeat this many times, as often as possible, so the dog learns that when he looks to YOU the treat is provided. He doesn't get to TAKE the treat, EVER. It is GIVEN by YOU... and only after he works for it (by focusing on YOU and not the treat).
If that is too hard, look up "it's yer choice" on youtube for a video on impulse control. You might need to wear a glove at first if the puppy is really pushy/grabby... but it doesn't take long for dogs of any age to learn to "wait" for you to provide a treat instead of trying to take it.
As for our bully rescue - he learned to respect me, but he never really loved me. We found him a new home with a couple that he fell in love with, and it was the best of both worlds.
If you can approach your GF's Corso with the intent of "winning" him over with love and not just gaining his obedience, you might have better luck... but... at some point, he's going to have to learn manners, too.