Man, I love thinking about weird cross-company matchups, and I dug into this one the hard way: there really isn't a mainstream, canonical comic issue that pits 'Deathstroke' against 'Deadpool' in an official Marvel/DC crossover. Both characters live on different publisher continents, and while the community loves imagining them duking it out, the actual comics haven't given us a straight-up, company-sanctioned one-shot of those two locking blades.
That said, don’t despair — there are tons of satisfying alternatives. If you want the vibe of a Deathstroke-style tactical assassin vs. Deadpool chaos, check out solo runs: read 'Deathstroke' (various volumes) to see his methodical, military precision, and run through 'Deadpool' (especially the runs by writers like Joe Kelly and Gerry Duggan) to get the full chaotic, fourth-wall-breaking energy. For fan-made matchups, webcomics, YouTube animations, Twitter art, and Reddit threads often stage dream fights and even create short fan-comics that capture what an official clash might feel like. If you want, I can point you to specific fan comics, YouTube battle videos, or a reading order that gives you the best sense of how the two would clash in personality and tactics.