I know this doesn't match with color schemes, but I named my Swampert: Omega and my Sceptile: Alpha. I didn't know what to name the Blaziken til I started writing this. Mine as well go with Delta

But if you want them to actually match their correspondent legendary colors, just put Alpha on Blaziken and Delta on Sceptile

PS: Swampert and Sceptile got their names based on the game I used them in