Bought a boat and trailer both unregistered was told by the RTA that the seller has to provide a pink slip so I can get a permit to tow it is this correct? Apparently now when selling any vehicle the seller has to provide a pink slip with that vehicle just wanted to make sure if this is right and if the seller refuses I can't be obliged to buy it is this right?

He has to have the title then you go with him to the notary. He signs over the title and you give him the money. The notary gives you the pink slip.
If he doesn't have a title (unregistered) don't give him a dime until he has it all straightened out.
You are not obligated to giving him any money if he can't even produce the proper papers.