、。。
One for all, all for one. That's teamwork.
Literal
One-person [topic-は] everyone [purpose-の為に], everyone [topic-は] one-person [purpose-の為に]. That [subject-が] team-play [copula-だ].
The famous Three Musketeers motto rendered in Japanese. 一人はみんなの為に、みんなは一人の為に mirrors the English structure neatly. The second sentence チームプレイだ defines the concept — the loanword チームプレイ (team play) is preferred over the more English-like チームワーク in sports contexts. The whole thing reads like a coach's rallying cry.