As it was mentioned above, the Mig-25 in soviet view, was designed chiefly to intercept the XB-70 Valkyrie. As the american bomber was cancelled, the Mig-25 was intended to SR-71 Blackbird.
Moreover, the arabs used the Mig-25. The syrian air force downed few F-15, and F-16 with it. The iraqi air force used the Mig-25 against Iran with mixed results. Maybe as the fighter was new in Iraq inventory, the skills of pilots were lights. The Mig-25 during Desert Storm, attacked B-52, F-111, and F-15. As US refused to acknowledge any losses aircraft due to iraqi air force it is hard appraise what's really happened. In Tom Cooper website he said that during Desert Storm, there are Mig-25 that attacked F-15 without success. The F-15 attacked the Mig-25 with a considerable shot of missiles, they finally successfully downed one Mig-25. There are other fights between F-15 and Mig-25, the F-15 failed to down the Mig-25 even with launching several dozens of air to air missiles. It is hard to evaluate the success of the Mig-25 because even though there would be a US fighter downed, US for evident geopolitical reasons refused to acknowledge any losses. Iraqi air force built up less than 100 modern fighters including Mig-23, Mig-25, Mig-29. Meanwhile US coalition deployed at least 3.000 aircrafts.
Another incident took place on the border of Saudi, in the end of 90's. A Mig-25 violated the No-Fly zone and penetrated into Saudi airspace. Jordan with their F-16 after launching several air to air missiles failed to intercept the iraqi aircraft. Then US sent against him F-14, F-15, F-18, all these aircrafts launched a considerable number of air to air missiles, but all missed the Mig-25, as the pilot successfully dodged them. It is noteworthy to recall that, these air to air missiles launched against the Mig-25 this time were AIM-7 Sparrow, AIM-9 Sidewinder, AIM-54 Phoenix, and AIM 120 C AMRAAM. The Mig-25 prove that US concept of air war by only using air to air missile against average manoeuvrable fighter is a real failure. What could we say against the very agile Mig-21, Mig-29, Su-27 ?
Moreover in soviet air force the Mig-25 served at interceptor, an reckon. Many Mig-25 intercepted several times the SR-71 without switching on its radar, only with their IRST, they could detect the Black Bird at more than 100 KM. US acknowledged that it lost several of its SR-71, in ....accident, because of .....the magic mechanical failure argument. These losses were certainly due to the air to air missile AAX-6 Acrid, hence by the Mig-25. The Mig-25 was 50's design with a limited goal, nowadays this fighter is no longer able to match with new air war requirements. The successor of the Mig-25 was the very effective Mig-31.