I think one of the earliest places in the game you can get this is in Canal de las Flores on the boat ride. There are tons of enemies just activate INTENSO as soon as the first 4 show up dodge right, attack, dodge left, attack. All you have to worry about are the fish so make sure you keep dodging. A charged enemy will show up before your first meter runs low so you can keep INTENSO the whole boat ride. Squeeze in head butts and uppercut when you can since they seem to add more to the combo that regular attacks. If you break your combo just quit and reload your save and you are right there again so you can try as many times as you need to. It took me 3 tries to get 200, but I always got above 100.
Hope this helps.