The bull charge is simply gravy for an ogre army. Its a nice bonus, but never spend points improving it, as it's too easy for an opponent to deny it.
Kadrium can verify for me on this one. I tried every way in the world to "focus" on the Bull Charge when I started playing a little over a year ago. I tried the Super Charge Tyrant (Bull Gut, Wall Crusher, Bruiser w/ Dragon Hide Unit of 6 IGs and a Bullgorger spell) and though I will have to admit, when it goes off there is no greater amount of devastation to be reaped from one unit; but when it doesnt and that unit gets mowed down, you honestly feel like you want to throw up. Kadrium is totally dead on with this (I now know from experience), the Bull Charge is nice when it happens - thats it. Please dont focus on it as a complete strategy in and of itself.
I've found it quite usefull to field a mix of 3 man units combined with 4 man units plus heroes. one of the ogres in the 4 man units goes to the rear rank. This adds a strength bonus to the bull charge, but more importantly it gives me extra wounds before panic tests start kicking in....I have never had the pleasure of fielding a tyrant.
This strat does work really nice, and is a viable option. Though I find myself using this more in friendly games against shooters than tournaments. (Says the Cormorant after the most recent list he played...

) As far as the Tyrant goes, you are in for a treat my friend

. I love how afraid people are of his unit!
Can anyone now advise how many ogres in a unit to use against Bretonnians? ... Hey has anyone beaten Brets here? Know any good strat, such as: tilting bait units of gnoblars?
I play against Brets almost as often as I do Weed Elves. We have three Bret players in my location. The most absolute and total piece of worthwhile advice I think I can offer is - for love of whatever deity you worship, do NOT let them charge you. They will break you 99% of the time, run you down, and kill you. Period. If you are feeling froggy and think they will not kill them all on the charge, you can let a unit of TC Bulls get charged and rely on Stubborn to keep you there so you can hit the flanks - but this is very very risky.
Piece of advice number two: Never rely on Gnoblars for anything against any army. Many a great battle plan of mine has failed in thinking those little green turds would do their job, and one bicker later...I'm picking ogres up off the table. The only strat they excel at is Table Quarter Capture - because you dont move them or fight with them to do it! Gnobbie are kind of like Bull Charges, they are nice when they do what they are supposed to do. Of course, my Gnobbies bicker more than most I think. Maybe I should get them some anger management... Seriously, against Brets, use Gnobbies to either draw Trebuche fire or threaten the Men at Arms units and keep them busy while your boys are killing knights somewhere.
Anyhoo, dont be afraid of the Blessing of the Lady. Let them let you go first. This gives you the opportunity to lure them into the positions you want them to be in. Send your bulls up as normal, but not as far, and tilt the IGs and get them ready to slam the flanks. Keep in mind that Brets charge our distance + 1/2 (18"), so you wont have to go your full distance all the time to get them to come out and be hit by IGs. If you do go your full distance, they can run those units down, and hit the guys that were supposed to hit them next turn! If you get flank charges on these guys, they break pretty easily.
The best spells (IMHO) against them are: Bullgorger (on the IG units - it practically negates their basic AS. If you can get this one on a unit of IGs with a Bruiser/Tyrant equipped with Siegebreaker - they become a knight slaughtering machine because he
does completely negate their basic AS! (str9!)); Bonecruncher (of course!); and Trollguts (if you do get charged or think you might, it can save a lot of wounds).
The Hunter can wreak some serious havoc on them as well because the Bolt Thrower part negates AS and can hit their ranks - most Knights are only T3, so you can probably wound all three knights in the rank. You can also use your Cav Kitties to do some character hunting and baiting - they move just as fast as they do with the bonus that you are Fast Cav.
So just watch for moving to far, and never let them go first. If they go first, they wont move far enough for you to charge, but they will almost be able to choose who they want to hit next turn.
Hope this helps!
Help me decide my next army to play! http://www.ogrestronghold.com/forum/index.php?topic=20309.new#new
Total Ogre Record:
40 W (15 massacres) / 15 D/ 12 L
Accomplishments: (2150 RTT) Maul in the Mall 2011 - Tournament Champion
Most Recent Game: 2150 vs. Beasts - my brother decided he wanted to try to beat my RTT list...yea, he didnt fair well at all. (Massacre)