I'm still unsure what you want to do with a group of 1 paly and 25 shamies.
- World PVP ? mostly inexistant on all realms, and i would think nowhere with 25 toons together on one side, so you'll get to one-shot a couple guys here and there and that's probably it. Then again you could do that with 5 toons.
Maybe would a mob get together and fight you? i doubt it will happen much really but hey, who knows.

- Battleground pvp? the only one you'll fit in is AV, and MBxing AV with 26 toons will probably become very boring after 2 games. in any case it's a long way before you get there, it's level 50 min.

- PVE? Raid that take 25 people start at level 60 and wont be easy if you're not geared from instances beforehand.
level 70 raids i can't see how 1 tank will work, not even talking about the lack of class makeup needed in every boss encounter.

Also, i think i've read in the previous pages about the paly used to tank in PvP.. hum, what? not sure i get this, especially with the fire power you have cant imagine you'd want him to 'tank' anything
If the paly is purely there to powerlevel the other 25 toons, then you should probably start leveling it now, and not buy the other accoutns for another couple months.

not sure how you will level your 25 toons. if it's buy grinding mobs, then 5 shamans will do as good as 25, they already 1 shot everything around. basically instead of dealing 1500 dmg to a mob with 1000hp (killing it), you'll deal 7500 to that mob with 1000hp (killling it the same), but you'll have 25 guys with a bit less mana instead of 5.
Do you have a plan, or an estimated time it will take you to have 26 level 70?

so, i'm a bit perplexed about this whole 26 boxed group..
If it's just an e-peen thing, then good on you, go for it and have fun.
but in that case no point worrying about the class makeup and horde/alliance, the server pop, the toon racials and all the posts in the couple threads about all this. Just do your 2 toons, get them to level x, plant your totems and take a screenshot. Done.

I feel like i'm looking at a man who has asked how to pilot a boeing 747 on an internet forum, got a number of answers, bought the plane and is sitting excited in the cockpit.
now I'm now looking at the plane, interested to see if it will move, and if it does, to go where?

Mad props to you if you get to kill Gruull or dominate AV though, or whatever equivalent there will be in WotLK.
In the meantime it will be fun to see you in Org.