The part of a sentence "he assembled a team" is grammatically correct and can be used in written English.
It can be used to describe an action done by someone to put together a group of individuals for a specific purpose or goal. Example: John assembled a team of experts from different fields to work on the new project.
With full support from the university, he assembled a team of younger scholars.
He assembled a team of advisers -- experts in technical issues, curriculum, testing, finance, communications and politics.
After monitoring similar problems, he assembled a team of three engineers to figure out what to do about them.
Last year he assembled a team of consultants and said he was considering a run for governor.
Within a month of his appointment, he assembled a team of about 200 specialists from across the government.
He assembled a team made up of several former colleagues, including Maple and Wasserman, and took on the city's staggering crime rate.
He assembles a team to get it back, consisting of the guys we've seen in the other movies (including Clark Gregg as Agent Coulson, the series's hardest-working nonsuperhero and its most reliable comic asset), as well as Ms. Johansson's Black Widow.
Once DiCaprio decides to take Watanabe's offer, he assembles a team of associates, past and present, who not only are experts at various technical skills necessary for the mission but several multitask by being experts at using their James Bondian/Ninja/acrobatic skills for mortal combat.
Yesterday he told congressional leaders he had assembled a team of lawyers to pursue a possible settlement in the case, parts of which were dismissed by a federal court in Washington last year.
Now he's assembled a team of the best bartenders from across the north.
He has assembled a team of a dozen employees who work in a high-rise apartment building in San Francisco.
