Gender: Male Location: United States
Lake Ontario, NY
Diablo can copy any pattern and invent new ones. He could overwhelm Ultron’s brain function and repel Ultron into a spiral that can eliminate any threat.
Might not be a good move for Ultron. For starters Diablo is functionally ageless with his potions.
Diablo can transmute elements through super-advanced alchemy, so he might actually have a weapon on him that can damage Ultron, shut down his nuclear reactions, or undo the molecular bonding of adamantium - he carries a lot of potions on him and he's done elemental transmutation before. Given the the nature of his character it would surprise me if in all the time adamantium has existed on earth that he hasn't come across it and studied it. It's been used by enough characters and organizations over the years and given the stuff is basically indestructible there is probably a lot of it around.
He has other abilities too such as teleporting himself and other objects and making himself immune to heat, energy blasts etc.
Not saying Diablo would win necessarily, but it could be an interesting match up, at least against more classic Ultron versions.