Ehhh... I agree a lot of crossovers suck, but at the same time, there is also a matter of balancing skill vs power, and a matter of exactly when the cross occurs for both series. Even more important, which canon continuity is used.
For Sailor Moon, especially if anime universe, even if they have raw power, I view them as incompetents when it comes to fighting, and their enemies tactics make them to be bricks for brains. I honestly do believe unless it is early series Ranma, he could stomp them unless they got a lucky hit in or beat him by superior numbers. Whether he can take a youma is actually a more interesting question, as there seems to be two schools of thought on it. I find either approach readable as long as the story is well enough written.
For Nanoha, they have power and training, but age and endurance might be a factor in 1st and 2nd season, by Striker S Nanoha and Fate should be able to take a Manga Ranma though unless he grew up with them, as is the case in some crossovers. I believe the Midchildeans in general, though not Nanoha/Fate, as morally corrupt and not evil, but perhaps anti-hero. Certainly uncaring of other governments though.
For Negima, I do not by any means consider Negi really all that powerful in anime as far as raw fighting goes. He has knowledge, and is a protege... but seriously, unless they gang up on him in numbers or some wacky single strike magical attack like turing him to stone, I do not overly think they could win.
For Dragonball, I actually generally dislike Dragonball, and Ranma crossovers with that series I mostly do not care for though a few have been ok. The problems are I agree as a human he cannot beat them and normally the excuse is either nekoken (yeah right), or they merely did not take him seriously (even if they thought him merely a bug, Ranma should be stomped in a battle). On the other hand, the ones I've seen with him as a Saiyan tend to ignore the concept or take away from all the hardship he went through in canon to get where he did in life.
For Sailor Moon, especially if anime universe, even if they have raw power, I view them as incompetents when it comes to fighting, and their enemies tactics make them to be bricks for brains. I honestly do believe unless it is early series Ranma, he could stomp them unless they got a lucky hit in or beat him by superior numbers. Whether he can take a youma is actually a more interesting question, as there seems to be two schools of thought on it. I find either approach readable as long as the story is well enough written.
For Nanoha, they have power and training, but age and endurance might be a factor in 1st and 2nd season, by Striker S Nanoha and Fate should be able to take a Manga Ranma though unless he grew up with them, as is the case in some crossovers. I believe the Midchildeans in general, though not Nanoha/Fate, as morally corrupt and not evil, but perhaps anti-hero. Certainly uncaring of other governments though.
For Negima, I do not by any means consider Negi really all that powerful in anime as far as raw fighting goes. He has knowledge, and is a protege... but seriously, unless they gang up on him in numbers or some wacky single strike magical attack like turing him to stone, I do not overly think they could win.
For Dragonball, I actually generally dislike Dragonball, and Ranma crossovers with that series I mostly do not care for though a few have been ok. The problems are I agree as a human he cannot beat them and normally the excuse is either nekoken (yeah right), or they merely did not take him seriously (even if they thought him merely a bug, Ranma should be stomped in a battle). On the other hand, the ones I've seen with him as a Saiyan tend to ignore the concept or take away from all the hardship he went through in canon to get where he did in life.