Which Universal Monster (either classic or from The Dark Universe) do you feel most equipped to take on?
Fair warning: I haven't seen a lot of Universal monster movies, so I'm basing this on a quick browse of the corpus.
If you mean "take on" in an adversarial way: I am not a particularly combat-equipped young woman, so the only means I have of "defeating" monsters is the Steven Universe method: converting them to friends. I think there are a number of monsters this strategy might work on, but the most likely by far is the monster from Frankenstein who is basically just a little kid who doesn't know his own strength. Even if he's not the enlightened soul from the novel, I bet I could at least calm him down and help find him a nice place to live with minimal chance of accidentally murdering children.
If you mean "take on" like as a pet: This is tough because I live in a city and so don't have reliable access to the wide open spaces needed to keep a werewolf well-exercised or the ancient castles that form a good vampire habitat. I think my best bet here would be the creature from the black lagoon—we've got some nice marshes a short drive away. A phantom could work as well, but the operahouse here is pretty modern and they tend to prefer older, more run-down enclosures.
If you mean "take on" like sexually: Dracula's daughter. No further questions.
Steven Universal