Yokoi asked Tajiri if he could make a multi-platform game (for NES and GameBoy) within half a year. Although he didn't have much confidence, the young and desperate game designer had no choice but to say "Yes". After some discussion about its details, Yokoi decided to give the job to him.
It was a bit of a challenge for Tajiri and his team because they had never made a game following a strict schedule determined by other people. However, they could not afford to fail it. So, he decided to temporarily halt all other projects including Pokemon to concentrate all resources of the company on the newest project, which became the last hope for him.
Of course, they managed to complete the task before the due date and the finished product was released under the name "Yoshi No Tamago (Yoshi's Egg)" for NES and GameBoy in 1991.
Youtube : Yoshi - NES Gameplay
Despite the limited development time and small number of involved workers, the game became a big commercial success as it sold more than four million copies worldwide. He got the money he needed and earned trust from people in Nintendo, which helped him a lot when he resumed the development of Pokemon.
But at the same time he lost the most precious resource of his company - the workers. Although they did understand the company was doomed, they couldn't endure the pain of being forced to work hard for low wages. As a result, the company lost all three programmers at once.
Needless to say, no video game can be developed without a programmer. Besides, they were not only employees but also true friends of him; they had spent years together making and talking about games with the same passion. To overcome the extremely difficult situation - both mentally and practically - he had to transform himself from a "game freak" into a truly professional business manager.
He renewed his determination to complete the development of Pokemon and made use of every opportunity he had to stabilize the business. Fortunately, his company had achieved a good reputation as a reliable game developer thanks to their high quality products including Yoshi and "Magical Taluluto", which was released by SEGA. So he was able to secure new contracts with those two large publishers.
Youtube : Magical Taruruto Kun (released by SEGA in 1992)
Youtube: Pulseman (released by SEGA in 1994)
More notably, he expanded the size of the company by an M&A to deal with those increasing number of tasks, which was a highly unusual move for a Japanese company back then.
Although he had to put aside the most important project, Pokemon, for a while (probably between two and three years) due to the shortage of financial and human resources, it later turned out to be a beneficial investment. The core members of the original Pokemon team such as Junichi Masuda(composer) and Ken Sugimori(designer) polished their professional skills during those days while the company achieved solid financial stability, which enabled them to invest a large amount of time and money on the big project.
It was when they finished the development of "Mario & Wario", which was also produced by Yokoi, that he got the absolute confidence in the future of the company.
Youtube : Mario & Wario (released by Nintendo in 1993)
Satoshi Tajiri (2003 @ GameFreak)
When we released Mario & Wario, I was able to see a clear possibility for the first time that we could finish the development of Pokemon
- Continue (Vol.9, p.157) Ohta Publishing in Japanese
The rest of the story is well-known : his game Pokemon, which eventually took more than six years to make, became a legend. But he has never lost sincere appreciation for the person who supported him in the difficult days.
Satoshi Tajiri (2002 @ GameFreak)
I learned the professional way of making video games from Mr. Yokoi.
- Continue (Vol.7, p.134) Ohta Publishing in Japanese
Satoshi Tajiri (2016 @ GameFreak)
Mr. Yokoi was like a second father to me.
- Game no Kikakusho (Vol.1) from Denfami Nico Gamer in Japanese
http://news.denfaminicogamer.jp/projectbook/xevious/3