I've found that green scrub pads tend to scratch plastics so are not that ideal.
As mentioned magic sponge (melamine foam) is less aggressive but still is a fine abrasive as thats how it works.
However I've noticed on some old plastics no matter what you use and how hard you try yellow staining don't come off.
One thing I've found when all fails that does shift staining on some is Cilit Bang Power Cleaner Limescale & Shine used with a magic sponge.
Just as a side note I've found using ubic 2000 too stronge can actually turn the plastic yellow too. Oops!...Yehaa