There's no formality about it. The President of the Senate is given the sole authority to preside over it, which gives him broad authority. He doesn't challenge anything, he simply discerns which are lawful slates of electors, and which are not. Which should be counted, and which should not be. There is no one else to determine if a proper slate of delegates was submitted correctly or lawfully before they reach the House floor.

There's no formality about it. The President of the Senate is given the sole authority to preside over it, which gives him broad authority. He doesn't challenge anything, he simply discerns which are lawful slates of electors, and which are not. Which should be counted, and which should not be. There is no one else to determine if a proper slate of delegates was submitted correctly or lawfully.