Any automatic transmission stop slip fluid out there that works?

It really depends on the situation, hardened seals usually cause weird stuff when cold, trans-X will fix it in 5 min. Lucas works other times, a clogged filter causes a slip after a few minutes and "fixes" itself when it sits.
Unless there's some other magic stuff sold elsewhere you are usually fighting a loosing battle that nothing in a bottle will fix.

Bring several spares.

If it's worn clutch plates, I've had the Lucas Transmission Fix buy me some time. What make/model trans are you having issues with?

Stop slip made one of my MB's go -  bang, whirrrllll.  Caution.  Soft parts are easy, blow a hard part and the price triples.

The stuff you need is only available in Diagon Alley... or perhaps Nocturn Alley..  Or you could just use your wand... It's magic any way you slice it.

I bought a 1992 Lexus ES 300 for $500.00 with 245,000 miles on it.  The car ran and shifted great when I first test drove it.  Got the car home and the next day it would barely move.  The trans fluid was not red anymore, it was black(maybe the previous owner put an additive in it).

Two transmission shops said that the automatic transmissions in these cars actually will not operate if the filter is extremely dirty.  I wanted to give one of the transmission shops some business, but I could not drive the car to them, so I ended up changing the trans filter, fluid and doing the trans service at home.  This car's transmission is shifting good again so far.

Good advice because some things eventually just need to be rebuilt.  The magic fix in a bottle does not work all of the time or will work for a very short period of time.

I'm big on proper car maintenance which prevents problems.  However my MacGyver car fixes started when I bought my 16 year old daughter a 1998 high mileage Mazda 626.  I became her personal mechanic to keep that car running.  That car ended up having a check engine light come on for an egr code.  The guy's on the Mazda forum said it was usually never the egr valve, but a dirty throttle body.  So I cleaned the throttle body and the check engine light went off (thanks again to those guy's on the Mazda forum).  The big rubber hose going from the air filter housing to the throttle body started ripping pretty bad when I tried to put it back on, so I glued that with JB Weld.  One guy on the Mazda forum said that I could not do that.  I told him that I just did and it held up just fine. 

I remember my dad broke a u-joint on his drive shaft out in the middle of nowhere on his 1972 Chevy pickup.  He just used bailing wire to temporarily fix it just to make it home.  My dad always has a roll of bailing wire, duct tape and electricians tape in his tool box.