Happened to stumble on this thread and this issue - perhaps the following is the case?
The moves that ricomanuel32 mentioned were:
- Turtwig line and Giga Drain
- Shinx line with Shock Wave
- Croagunk line with Focus Punch
Vytron I think you may have been looking at learnsets for Gen 5+. None of these moves exist as TMs so it's natural for the move to not appear on a given Pokémon's learnset. However if you look at the Gen 4 learnsets for these Pokémon (the generation they were introduced), then you can see that all of the moves listed above are able to be learned by the respective Pokémon.
What you do next is up to you but I think that if you're going to include TMs from a prior generation then you should use the TM list for the earliest generation possible. Though this does get tricky (assuming you're using the "by the book" method of strictly looking up learnsets) if you import, for example, Gen 5 mons with Gen 3 TMs.