Elimination chess tournament, featuring: Adam Warlock vs Martian Manhunter, Thanos vs Dr. Doom, Bruce Wayne vs Reed Richards, Brainiac vs Darkseid
No TP, magic, tech, or superpowers of any kind. All eight have had all knowledge of the game from their minds and are given a month to learn the game from scratch. Players know who their opponent is but don't know the identities of the other participants.
Bruce Wayne vs Reed Richards: Ok, listen: Reed Richards is way, way, waaaaay more intelligent than Bruce Wayne. They aren't evolving in the same league, at all. However, even if Reed is a great tactician himself, being the leader of his team, IMO, The Goddamn Batman is a far more better strategist. So, I'll give it to the Goddamn Batman.
Brainiac vs Darkseid: Darkseid
As for the rest, Thanos stomp and win this chess tournament.
People put too much value on vague statements like "strategic mind." If we learned nothing else from Deep Blue, it's that there's a point at which sheer processing power or chess "intelligence" trumps a more creative, "strategic" mind. There's only so many logical moves in each scenario.
In a comic fight, with more variables and unknowns, someone like Batman has an advantage. At a much more objective endeavor like chess, he does not. Reed blasts him hard at this.
I got Brainiac, personally. Reed and Thanos have a decent shot.