Miss Fortune needs a buff
It is a slight adjustment, but for me a big game changer... TL;DR can be found on the end.
As you can see Missfortune is at lvl 1 the worst ADC with only 54 attack dammage (ofc without runes and items) and even on lvl 18 she ONLY has 88 dammage (Sounds crazy but maybe that is an intended crazy nazi pirate joke... i'm German with black Humor i know what i am talking about, but i am drifting away from the actually diskussion) Her attackspeed is also not the best(second worst if i remember), attack range is also one of the worst. Iff i remember correctly, just on pure base stats she is the worst adc there is. Okay her Kit looks good, but even then there could be some adjustments be made. Like the Base dammage of her R, or slow effect of her E, than you could iff you buffed R and E to much nerf W attackspeed and Q dammage a bit. Her Passive is 100% perfectly fine as it is now. Great Bonus dammage for switching Targets every shot, but with a good drawback of her basic Attack Range.
NOW iff we look at TEEMO as and ADC, than following things gonna happend... He is better in Attack range , Speed and base Dammage than MF is. His ability may not scale with AD, but even than his Kit is well rounded that he actually doesn't need that as an ADC. Passive gives him attackseepd, Q blinds enemy Carry, W gives Movemendseed to reposition or kite and hunt down low enemy champions, his E is good extra dammage per shot (not so good as a DOT but for an ADC still pretty good for the extra MAGIC dammage against Tanks) his R can be used as Wards, Slowing traps or Wave clear!
lets compare that to MF
Basic stats are all worse than Teemos stats. (And Teemo is not supposed to be an ADC, but iff i would take another real ADC you can immeditly see how weak MF is and buff her so hard she will get to the IMBALANCED LANDS! where she will get banned in Ranks 24/7. and yes that is what you LeagueOfficers do, i know that becouse i played since the Beta. Proly you aren't happy with Mf as well but you can not care at this momment, becouse you still have to be KEWL and i kinda appreciat that) Passive is very good extra dammage but only iff 2 targets are available plus it is hideous that you have to target A than B than A than B again jadi jadi jada ... but iff possible to use than this would be a VERY GOOD passive. Her Q first hit is laughable... the Second one so, is actually OP dammage... but it nearly never comes to that you can hit an enemy Champion with the second hit. Her W is a very nice aktive, and a more less nice passive, but still A-OKAY to me. (her attackspeed and movement speed could scale with ap for me, just joking but the punchline is coming with her R) Her R IS SO WEAK that 0 Teemos are getting kills... so her R is 0 Teemos per second!!!! ZERO TEEMOS you know how much that is? Yes ridiculously ZERO TEEMOS!!! Okay jokes aside... her R is without items on lvl 18 only about 300 Dammage total... but that is not even good becouse it takes 3 SECONDS CHANNELING till those 300 Dammage are inflicted. So she needs at least 3-5 Targets that the dammage is good dammage (so in a teamfight) but than the enemy team needs to be bad positioned, bad team comb or her team needs to be good team comb, and at least 3 Champions that her R is worth using... or else you could technically use it on Minion Waves to clear the lane and be faster in teamfight again... but for that her CD is to high on the R. (okay i am gonna stop here i am PRETTY emotional now, will revise this another time, proly than when i see it on Redit) So she needs to stay perfect for her R to be good, 1 Stun or knock up or something and her R is worthless... actually you don't even need to stun her... only get out of the R area, and that is actually pretty es 90% of the time.
So TL;DR Buff MF attackseepd a bit and base attack dammage, for an better early Game. Her R can stay as it is for ADC (But for APC it is still very weak compared to other MASSIVE dammage Ultimates)