I would put Morg over Thor or BRB, but Terrax under both, which means that Morg will soon be tag-teamed and defeated. The REAL QUESTION here is, where are they fighting? If they are fighting in an area with very large amounts of dense minerals, then Terrax's earth-control might even things out enough to give their team a few more wins.
Originally posted by Endless Mike
They fight in the Hoth asteroid field from Star Wars
If you're being serious, that changes everything. In an asteroid field Terrax can attack from all sides. One on one he would still eventually lose against BRB or Thor, but in that environment I'd guess it would take long enough that Morg would best his opponent first, allowing him and Terrax to tag-team the remaining hammer-wielder.
Team Axe 7/10