What is the instrument Teddy Riley played like an organ guitar?

Answer 1

it's called a "key-tar"/shoulder synthesizer and companies such as Roland and Yamaha have had several models over the years. Many of the "key-tars" seen in public performance are merely MIDI controllers (not housing a synthesizer engine, but operates one remotely) while very few use models with onboard synthesizer engines due to the increased weight seen in the original key-tars (as well as the characteristic drawbacks to analog synths)

Technological advances have allowed for shoulder synths to reduce in weight, while still housing powerful sound engines, such as the Roland AX Synth, which is popular with several nationally-renown artisits.