Tips to Help My Playgroup?

One of my friends is an extremely strong deckbuilder who has been playing since childhood, and therefore has a lot of very strong cards and a strong understanding of their synergies. However, some people in my playgroup lack the time and money to build comparable decks, and others just enjoy playing less optimal decks, but my friend will not power down his decks. He recently built a [[sekiko mother of summer]] deck that he calls a 2, but it still easily thrashes most of the decks at our table. So far, the solution to this is either to accept defeat or to gang up and take him out ASAP, but neither solution is optimal since it always leaves someone upset. I have a few decks at different power levels so I can usually pull out a better deck when my friend does, but it always leaves me feeling bad for the rest of the guys since it just means that they have more threats to worry about. Does anyone have any suggestions on how I can approach this situation?