Yokohama to Tokyo by Pasmo/Suica IC

Can I buy this IC card at yokohama station? and can I use it to go to Tokyo from there?
I heard people says that IC cards only work in Tokyo so for long distance we must buy separate ticket. Is it right?

Yokohama to Tokyo is short distance and IC cards can be used in many parts of the country (not universally, but quite wide). Easy to get/buy and re-charge with funds.
You wouldn't use SUICA for something like Yokohama to Kyoto.

1)
You can buy it and both IC cards covered most public transportations, except taxi in Tokyo and around.
Yokohama is one of Tokyo around, same card validity area, no worry.

Suica saler is JR-EAST(biggest rail company in Japan east),
PASMO salers are non-JR rail and bus companies group,
pls read both official web and online guide books.
https://www.jreast.co.jp/e/pass/suica.html
https://www.pasmo.co.jp/en/

And Yokohama stn is not only one rail company, be careful.
https://en.wikipedia.org/wiki/Yokohama_Station
http://www.yokohamajapan.com/information/travel-to-yokohama/

2)
Basically so, using one IC card can not allowed over the card border stn,
it means validity area is own card area only, and have to buy old style paper ticket(s).
Only some exceptions, such as SmartEX service for Tokaido Shinkansen,
but temporary travelers do not use these usual.

However, both cards also works in other regions major card area.
(official web and guide book mentioned)
In other region card area, you can re-charge
at most rail stns, bus payment machine and major covenience stores.
yet you can not card return(refund) and re-issue when broken or lost.

(note)
Both and other simlar functions IC cards do not make fare big discounted,
just easiest way to payment and safest if without wallet as own customarily.
https://youtu.be/9TuVRCXynpA
https://youtu.be/s-NyccWXlt4
https://youtu.be/rvqitrtmziY
(2nd video guy did some wrong tho but mostly useful, just not perfect and worthful)

So if can not find a best discounted ticket, should post again here ASAP.

Yes, you can buy either a Pasmo or a Suica card at Yokohama Station. Both cards work almost the same way, and you can used it to travel from Yokohama area to Tokyo area.

Thanks a lot to all response. Now, I have a lot of confident when come to Yokohama station. I will take train MM05 at Nihon Odori station (10:14AM/platform 2) to Yokohama then take JT05 (10:32AM/platform 7) to Tokyo. All trip will be paid by IC card. Is any chance I will board a wrong train(opposite way) at these 2 stations? Thanks.

Is any chance I will board a wrong train(opposite way)
Unlikely - there is lots of signage and platform sides are often direction specific.
Getting the wrong train is also not the end of the world, just like missing a stop. You just get off and wait for the train going back the other way - quite simple. Plus, many of the train lines in Tokyo (greater Tokyo including Yokohama) are very frequent so I usually do not bother worrying about the time of a specific train.

Once you arrive at Tokyo Station and decide to take a Yamanote Line (loop) train, then you need to know which loop (outer or inner) to take. I don’t understand why they don’t call them clockwise loop and counter-clockwise loop, but the outer loop (soto-mawari 外回り) means clockwise, and inner loop (uchi-mawari 内回り) means CCW. I always find them confusing. But even if you take the wrong direction train, you will eventually arrive at your desired destination.

Is any chance I will board a wrong train(opposite way)

No, as long as you're on the correct platform number.

Getting the wrong train is also not the end of the world, just like missing a stop. You just get off and wait for the train going back the other way - quite simple.

Actually, it's not that simple at all. (To viewers wondering why, there are so many locals who go back and forth riding wrong trains at platform 9, Yokohama Stn.) Whenever you think you're lost, ask someone around you. It would be better if the person is a uniformed staff. Just ask "Tokyo Station?" and language wouldn't be a problem.

Note that you can buy PASMO at Nihon-Odori Station, too. And note that you can take direct trains from Kannai Station (which is walking distance from Nihon-Odori Station) to Tokyo Station. You can also buy a SUICA at Kannai Station.

Thank you all for the trememdous valuable advise. Per Uno I can walk to Kanai station to take direct train to Tokyo. I wonder how the condition of the streets there because I will debark at the Osanbashi International Passenger terminal on Sat 3/28 and I have a suitcase to pull along with. Thanks.

With a suitcase and coming from Osanbashi, I would catch a train from Nihon-Odori instead of Kannai. And at Yokohama Station, I would try to use the ticket gates that are closest to Tokyo (which are the northern exits), because there will be less crowd and transit to JR trains bound for Tokyo would be easier that way.

But if the weather happens to be harsh (such as rain), I might catch a bus or taxi from Osanbashi directly to Yokohama Station.

By the way, you say you are doing this on March 28, 2020. Please keep in mind that train schedules may change by then, because schedules tend to change about once or twice a year, although not dramatically.

For the zillions of commuter trains running between Yokohama and Tokyo no-one would be worried about a possible schedule change. Turn up, get the next one. Depending on the time of day, you might have to wait a few minutes.