There are many types of VRY (Vipareet Raja Yoga). If VRY has parivartana yoga then it becomes stronger. Here are some examples, all taken from the Rajayoga chapter of BPHS (Brihat Parashara Hora Shastra).
(1) Malefics aspecting or conjoining 3H or 6H. (This condition is exclusive and does not require other simultaneous conditions, but all the following rules require some other simultaneous conditions.). But 11L in Trika (Trika is 6H or 8H or 12H) is Daridra Yoga.
(2) Malefic in 6H.
(3) Neecha (debilitated) planet in 3H or 6H or 8H.
(4) Lords of 6H or 8H or 12H either combust or neecha or in enemy's sign.
(5) Neecha lord of 6H or 8H or 12H aspects lagna (Derived meaning ; if it aspects some other house, that house will gain).
(6) Neecha planet in 3H or 6H or 8H or 11H aspects Lagna.
(7) All malefics in 3H, 6H and 11H (and all benefics in kendra).
There are many more VRY rules. BV Raman Ji has summarised those rules in his famour book on 300 yogas. For instance, he defines Harsha, Sarala and Vimala Yogas as 6L, 8L and 12L respectively in Trika houses. These yogas do not make rajayoga by themselves alone.
There are many other rules which modify the results of above yogas.
If all conditions of rajayoga are not fulfilled, it will work only partially. Fruits will come during dashaas of planets causing rajayoga, and during those dashaas best results will be felt when VPC and AV also cooperate.