Question

Can I transfer Pokemons from poke bank (pokemon of xy and or/as)to Pokemon yellow?!?

Answer 1

No. This is because the stats move abilities and Pokemon are different and it would break your Yellow Version. In Sun and Moon you can take your Yellow Pokemon from the Virtual copies and put them in Sun/Moon.

Answer 2

Exactly what mrbones said but also

when Pokemon moon and sun come out you will be able to transfer your Pokemon from

Yellow/Red/Blue to Moon/Sun

So its not a complete worry, your not wasting your time playing them..

as to answering your question though unless you bought a gameboy advanced colour and purchased a copy of yellow/red/blue and then used a cheat device then you cannot cheat.. however there are ways on youtube on how to glitch Pokemon like MEW into gen 1 games and then ready for gen futures..

goodlucky happy gaming, not sure if I helped but its a collection of opiniated views.