For trying to lateral as an associate, do I really still need to include GPA?

Based on on-cycle recruiting timelines for PE, PE firms are recruiting bankers who are literally 0-12 months into banking. Plenty of PE firms make mistakes when hiring A1s, because candidly, there are very few datapoints to assess the true potential of a brand new banker (and effectively recent college grad). If an associate is then looking to lateral, the bar is actually even higher, because well-performing PE associates are often less likely to leave their current shops (strong promotion track, good work begets more work and heavy staffing, etc.), so there's an adverse selection within the lateral pool and GPA becomes one more data point to assess candidacy (in addition to work experience, communication skills, references, reason for wanting to lateral, etc.).

I'm sure all firms are different, and it becomes increasingly less important with tenure. It also isn't a dealbreaker, but lower GPAs typically need to have a compelling story and/or ideally have strong test scores to offset concerns around intellectual horsepower.