I worked on The Simpsons Game as a tester on a small team at EA with two or three others and a test lead. While we helped test all the different platforms (X360, PS3, PS2, PSP, Wii, NDS), we spent most of June-October 2007 on PSP.
You can group those platforms into 3 categories:
X360 and PS3 were next-gen and had extra levels, powers, and a hub map missing from the others.
PS2, PSP, Wii were all the same codebase and developed at Rebellion. Their content varied based on features and capabilities.
And this is where my team's platform fell in the hierarchy of importance:
6. PSP (oof)
PSP wasn't shafted or anything, it was simply a matter of production necessity. As the most low-end device in that group, PSP required extensive optimization. It took a while for the development churn on other platforms to settle and for those changes to get brought over to PSP. We'd wait weeks between builds, staring at the same content on the small PSP screen day after day. You learn to test creatively when you're treading the same ground over a long period. (We did have bug quotas.)
But as a small team, we had less scrutiny. Praise the bureaucracy!
PSP is by far the most limited version of The Simpsons Game, but I'm still weirdly proud of our work. There were a lot of constraints and helping to see the PSP version through to a release just felt more satisfying than it would've been on the major platforms.