Yellow "starters" missing in database?

[Xelloss]

I just discovered the encounter database in PKHEX and I cannot believe how complete it is... However I found there are no encounter (even when trades and statics are in the database) entry for bulbasaur, squirtle and charmander in the database of Yellow.... 

Is there any reason? as far as I know you can trade them and move it to other games (not like pikachu), so they should be legal. I must be missing something there...

Edited February 27 by Xelloss

[Kaphotics]

Simple answer: deduplication.

There is no difference in data of a RGB starter that has been leveled up to level 10, in comparison to the Yellow gift encounters that are also at level 10. They can most easily be recognized as the level 5 encounters in both cases, so there's no need to have the level 10 encounter later (which will never be matched, because the level 5 will match first).