Many western countries found themselves in pocession of Soviet equipment after the Cold War either because they had been former Soviet vassels (Poland, Czech Republic), form reunification (Germany), or from buying the hardware to keep it off the open arms market (US, UK, Italy). In some cases that material was just scraped, in others some was kept around to practice against. In others it was incorporated into their armed forces, if I remember correctly Germany had and maybe still does about a dozen Mig29s in the Luftwaffe proper (which is another reason why imagining relying on simulations is not stupid).
EDIT: Germany's Mig29s were sold to Poland a few years ago, here is a pick with Luftwaffe markings.