Just straight-up curious since I almost OHKO'd Azelf in Platinum with my Weavile earlier today. Please include event mythicals/legends and roaming ones too if possible!
Experience yields were reworked starting in B/W to take a more formulaic approach that's generally derived from base stat total and evolution stage. Sw/Sh changed it again, but only for Pokemon in the final-evolution bucket (which is of course where most legends reside), so there are three lists depending on what game you're getting the experience in.
The Exp. column is the one you're looking for; in games that follow the first list, you take that number, multiply it by the level, and divide by 7. In later games after the numbers changed, you divide by 5 instead of 7, and for all such games except XY and ORAS, do some further scaling that depends on whether you have a level advantage over them or a disadvantage.