Here's one that is higley debateble: Kyogre vs. Groudon. Most would like to say Groudy can own Kyogre. Classic battle for Groudy vs. Kyogre:
Groudon goes first since faster: Uses Swords Dance or EQ.
Kyogre survives EQ or SD: Hydro Pump (if hits) would kill Groudy, as would Water Spout unless he is hit by an EQ first. Ice Beam also does a Hell load of damage.
This battle may depend on EV's or the movesets/ uses of moves. Very easily it could go either way.
Baby I like it.