Note that keeping a pair of pearls may prove problematic later on. The male willt end to chase the female around. It helps to have at least 2-3 girls per male to devide his attention. Gouramies are not like cichlids - they don't 'pair up'. This, BTW, won't mean they get in teh kribs' way more - only male pearls are territorial in the strict sense of the word - the females won't be competing with the kribs for 'their' space except in terms of swimming room - which is the case with any tankmates anyway.
Good dither fish for a tank like this need to be non-nippy and not top-dwelling so they don't bother the gouramies. I'd go for some schooling rasboras or tetras. Maybe something like emperors, pristellas or non-nippy barbs like checkers. You could also try neon blue or possibly threadfin rainbows, or another simialrly-sized rainbowfish.
American-flag fish, swordtails and cherry barbs, though non-schooling, would also work. Avoid anything slow or particualrly long-finned (eg guppies) which could easily get picked on by breeding kribs. Keep in mind that danios, dispite their suitability as dithers, are not ideal tankmates for top-dwelling gouramies like pearls.