No, because Pokemon only learn level-up moves when they, well, level up
If I understand your question right, you're asking if Sunkern, when evolved into Sunflora at level 10, will learn razor leaf upon evolution. Sadly, he will not, as he would have to go from level nine to level ten as a Sunflora to learn it by level up. As such, upon evolution at level 10, it will retain mega drain but not learn razor leaf. However, it is still possible for it to obtain razor leaf and mega drain on a Sunflora You can either a. use the move reminder from Stadium 2 after beating that game's champion, or more easily do B., breed a Sunkern that has mega-drain. If both parents, one of them being a female sunkern/sunflora, know mega drain will pass it on to a baby sunkern Before level 10, evolve this baby sunkern into Sunflora, and at level 10 it will learn razor leaf, and you will have a sunflora with razor leaf and mega drain.
Basically, this is not possible, but you can get a Sunflora with both moves if you breed a Sunkern baby with mega drain, evolve it before level ten, and teach it razor leaf when it levels up at level ten as a sunflora.
I know thats confusing but I hope this helps, and I hope my memory serves me well, as it has been wavering as of late