The phrase "also joined forces with" is correct and usable in written English.
It can be used to indicate collaboration or partnership between individuals or groups, often in a context of working together towards a common goal.
Example: "The two companies also joined forces with local charities to support community development initiatives."
Alternatives: "collaborated with" or "teamed up with".
They've also joined forces with their newspapers.
The legislators also joined forces with Mr. Bloomberg to push through the bill giving the city fiscal relief.
Veolia has also joined forces with IBM to deliver new digital urban systems to transform water, energy and waste management services for cities.
Never ceasing his composing, Tchicai has numerous releases leading groups of younger players, while he also joined forces with people like Johnny Dyani and Cecil Taylor.
His extra-curricular activities don't stop there: Reznor has also joined forces with new streaming service Beats Music, who have recruited the artist as its "chief creative officer".
The Congress also joined forces with B.J.P. defectors, including those accused of complicity in the 2002 violence; the tactic yielded virtually no benefits at the polls.
PHE has also joined force with a number of partners, including the BBC Get Inspired brand, Asda - which will be providing free blood pressure checks - and Slimming World - which is providing discounted access to its schemes.
He also joined forced with Pacha's Eddie Dean to form RPM Presents, which put together events at Governors Island, Pier 92, Central Park, MetLife Stadium, Citifield, Radio City and various warehouses.
Fighters from Islamic militias are also joining forces with Isis.
Gibbs is also joining forces with former White House spokesman Ben LaBolt to form a "strategic communications" firm.
She also joins forces with an actual detective, who is played with stubbly ambiguity and genuine heat by Ron Livingston.
