Jigglypuff has the best risk reward in the game. Not only because she has an O-KO move, but she can often choose which situations to engage in and exploit the best ones with the best risk reward and the ones where she is winning a lot of the time.
Risk vs Reward can be applied to every situation in the game and thinking about it before every neutral interaction is important. The risk and reward changes based on % a lot due to rest, when shes at a percent where she won't die due to a miss rest. This allows Puff exploit certain spots where at high percents she would lose her stock. If she misses rest or your opponent hard calls out what your doing, but at low % you wont die and if you hit the rest you take a stock. Pretty much this turns a high risk, high reward option into a medium risk, very high reward (even higher because you will trade if you hit it at high percent)
Knowing what situations across all the match ups have a good risk reward is essential to playing the character. Against higher level opponents they will know before hand what these spots are, it is your job to adapt to how they try and avoid the situation or how they adapt back in those situations.
This also can be used against your opponent when you are nearing death percent. People will often try and exploit Puffs big weakness in being super light. If you can make it harder by playing safe and patient you can try and make them over commit and go for an option that has a lot of risk involved that you can turn that into a stock.
Thank you for reading! Next part will be on choosing situations and exploiting winning/good situations :)