The way the math works out, you virtually always want to be making 1:1 attacks.
With this premise in mind, look at the attack values on the conventional units and the defense values on the Ogre systems, and some tactics will immediately suggest themselves:
- HVYs are optimized to take out main batteries, missiles, and treads.
- MSLs are optimized for secondary batteries and treads.
- Full strength INF platoons are optimized for SBs, and treads.
- GEVs don't seem to be optimized for anything, except, as noted above, if you send them in once the Ogre's strike range is less than the GEV's retreat range (which is to say, the MBs, missiles, and one movement point are gone), they can attack treads with impunity. That's very powerful. You can also pair their fire with single infantry squads to make 1:1s on SBs.
- Howitzers are an extravagant waste of firepower on anything except treads, but if the Ogre has missiles remaining by the time it gets under a hostile artillery umbrella, those need to go first, by any means necessary. [A surviving missile is an instant win for the Ogre 5 hexes away from the CP. A surviving tread unit is only an instant win for the Ogre at 1 hex away from the CP (assuming, as we should, that you didn't waste firepower eliminating its AP guns).]
Taking out an Ogre before it gets to your CP requires using your firepower /efficiently/. You have just enough to do it, but you can't afford to waste any.
Your initial first priority is always to lower the Ogre's strike range. You can do this by destroying treads and/or by destroying the MBs and missiles. Obviously, you'll have to do both. If you want your force to survive long enough to eliminate all the treads [which is necessary to win] you /will/ need to destroy all of the MBs, all of the missiles, and at least some of the SBs. Knowing when to switch your priority from SBs to treads is the most complex decision in the whole game.