I'd suggest you talk to someone that knows how to create a bonsai but my guess would be you are dealing with two very different groups of plants.

What I know for certain is Alocasia Poly is only a natural form of Alocasia Amazonica. I traded mail with my friends Denis and Bill Rotolante at Silver Krome Gardens just this morning who found the form now sold as Alocasia Poly (correctly with one L, not two) to confirm this information. The only difference is "Poly" is a smaller variation.

The "poly" came from the term polyploid which indicates a plant has double the normal chromosomes. However, in the case of Alocasia Poly DNA tests proved otherwise. The plant is just a natural variation of a plant that was originally hybridized by Salvadore Mauro in Miami, FL in the 1950's at a nursery named the Amazon Nursery. Thus the name "amazonica". There are no natural Alocasia species in the Americas since all 100 or so species come from SE Asia and/or the islands in the near Pacific region.

If you're interested the entire story it is told at the link below but I caution the story is evolving each and every day so I'm now forced to update the page daily.

It is likely a story will be published by another author on the International Aroid Society website in the next few months about this "sordid affair".

As I said, if you want to dwarf a large Alocasia confine it to a very small pot and it will never get large.....I have Alocasia 'Lime Zinger' in a 3 inch pot......have had it that way for 2 years.....the largest leaf is around 3 inches.....if this is what you want (mine is like that because I got it for free and just had no interest in it at all so have never bothered with it) then you can do it :o) Dan