In most places the basic requirements for teaching are a degree plus a certificate, however not having a degree does not always prevent one from teaching and there are many teachers working around the world without it.
What often happens is that schools will be looking for teachers to start at the beginning of the school year (often after the Summer) and then again after Christmas (this is when some contract teachers decide to leave and the school is left with an unexpected vacancy). Obviously the schools will go for the most qualified candidates first, but if demand outstrips supply, they will be willing to employ teachers without a degree.
You should note however that often holding a degree is a visa requirement and not so much a school requirement.
China, Vietnam, Philippines, Thailand and Indonesia are said to be countries where you can still be employed without a degree.