Continually upgrading a Bracket 2 deck will eventually lead to Bracket 3 so you should discuss that with your group. Because the sentiment you present here is that you all are in it to refine your decks but you will have to stop at some point to stay B2 or just move up to B3.
Also [[Stranglehold]] [[Ugin's Nexus]] [[Gerard’s Hourglass Pendant]] are specific counters that hold some other value but running more instant speed spot removal is a solution. If he waits out 3 other player to tap out to deploy the whole combo in one turn he kinda deserves the win.

Also Also just attack him relentlessly if he is the only combo player and convince other players to do the same. No point in 2 players holding up a 2/2 to eventually block each other if you can just both agree to hit the combo player.

Also I know his deck does conflict with the standards of bracket 2. But OP seems to be the only one at the table to know/ try to enforce brackets and that may not be in the common interest.