Currently Online 
A few reasons.
One is there is a higher chance of multiple handhelds in one household than consoles. If you are a family with 3 kids and looking to get a console for them, you most likely would just buy one console and a couple controllers. With handhelds, especially when they are cheap, you may get one for each child.
Another reason is people buying revisions. Nintendo home consoles rarely get revisions and when they do its usually extremely late in the generation. Nintendo handhelds on the other hand have about 3-5 different versions throughout their lives.
Pokemon is another huge reason. Since 2000, mainline Pokemon titles always sell over 15 million, remakes over 10 million and expanded updates over 6 million. Its the 2nd best selling franchise with over 300 million units sold in the last ~20 years.
On top of that, alot of people simply enjoy portability and being able to play wherever they go.
When the herd loses its way, the shepard must kill the bull that leads them astray.
