If you're wondering about all the missing questions and plot holes of ash's past, Previous companions like may, iris, max, clemont,serena ext.
(You can watch the last 10/5 minutes of the last episode with only ash, its a nice moment, but thats about the only good part of this)

Don't bother, these episodes are just made just for pure nostalgia. It's basically season 1 and 2 with better animation and visuals. Brock and misty come back,they go on an adventure together bla bla bla.
These episodes are basically filler, you're literally missing nothing, you can skip these episodes if you want.
Don't waste your time on these episodes

But if you're a hardcore genwunner then do watch it, its made for you guys.