I tried some experiments today with colored paper stuck on the wall. I did take some video but it is pretty long and boring

So I will just post my findings. I did two tests per color per Pleo. I did not turn them off between tests and I kept them separate during the test. The reactions listed are the ones immediately after both Pleo's 'sniffed' the color. Both Pleo's were fed on request and petted on request throughout the experiment
Orange Test 1- Lilo backed away, Stitch growled at it (angry growl not playful growl.) Test 2- Stitch backed away, Lilo became upset.
Yellow Test 1- Lilo sang to it, Stitch did playful crouch on front legs and wagged tail in air. Test 2- Stitch sang, Lilo made happy barking noises.
Green Test 1- Lilo ate, Stitch ate. Test 2- Lilo ate, Stitch mooed.
Blue Test 1- Stitch backed away, Lilo ignored it. Test 2- Stitch backed away, Lilo ignored it.
Red Test 1- Lilo backed away, Stitch ignored it. Test 2- Lilo back away, Stitch became upset.
White Test 1- Lilo ignore it, Stitch ignored it. Test 2- Lilo said hello, Stitch ignored it.
Black Test 1 & 2- Sniffed then ignored on all accounts.
Based on these limited tests I would say that Pleo's in general do not care for warm colors (reds/oranges), they like greens, blue is unconfirmed, they like yellows and black and white are pretty neutral.