I lost the original message but I think I've a few
ideas: as you said,
Ranma ==> Sheridan
Akane==> Delenn
Happosai as Kosh is good, alternatively how about
Kosh==> Cologne, both wise and powerful.
Ranma:  Look you old tin bucket, I demand a straight answer!
Cologne whacks Ranma with her mental staff:  Who are you
calling an old tin bucket?  I *said* all answers are replies but
not all replies are answers.
Garibaldi==> Ryouga
Ivanova==> Ukyou
Dr. Franklin==> Dr. Tofu, who instead of a "stim problem" now
has a Kasumi problem...
Ryouga:  Damn it Tofu, I'm your friend!  Now tell me what's wrong.
Tofu:  I don't know how or when it started.  But whenever *she*
walks into the room, my glasses fog up, my brain shorts-circuits,
in short I become a babbling, clumsy fool!  It's affecting my work,
the welfare of my patients and my life!!!
Psy-cop==> Kasumi. Which explains her serenity, she already 
knows most everything.  She's not exactly evil but not totally good.
Morden & Associates--> Nabiki and her cronies.
Londo==> Kuno (Tatewaki)
Vir==> Sasuke
Nabiki:  What do you want (Kuno-baby)?
Kuno:  I want to restore the glory of the Kuno Family Empire!
Sasuke:  But do think that's wise, Master Kuno?
Kuno:  Silence you underling!  Do you question the wisdom of
the great Kuno Tatewaki?  I shall be the one to lead the
Kuno family back to greatness! Bhahahah!!!!
Drall==> Mousse, both Mousse and Drall have a theatrical 
quality and like to use seemingly "magic" stuff.
G'Kar and Narns==> Shampoo and the Amazons.
Now if Ukyou is Ivanova then...
Marcus==> Konatsu
Ukyou:  I don't think I feel that way about you Konatsu...
Konatsu:  I can wait! (BTW how much do Rangers get paid?
A whole 5 yen piece?)
Other Rangers==> Genma and Soun, they both like to 
play spy and more importantly eat "spy food"! (see
One Flew over the Kuno's Nest)
Babylon 5 Crazies and Lurkers==> Kodachi and any
number of weird Ranma characters.
Lennier==> Gosunkugi.
Gos:  I know she's fated for another but I'll always be
by her side!
President Clark==> Principal Kuno
P. Kuno:  Not only do I declare martial law for Earth, but
everyone must be given a really bad haircut! Bhahaha!

Mind you it's like fitting square pegs into round holes.
All the characters need major re-vamping.

--Ilsa, who really needs to get out more. COR and OAA