You could use “With the team’s assistance…..” Or

for a different approach: “Working

in tandem/ alongside the team….” However no,

in assistance is not a good use of English. Nevertheless by substituting assistance, we can construct a better application:

“in co-operation with the team….”

You could use “With the team’s assistance…..” Or

for a different approach: “Working

in tandem/ alongside the team….” However no,

in assistance is not a good use of English. Nevertheless by substituting assistance, we can construct a better application:

“in co-operation with the team….”