Why would Simba ask Hyenas for help though? After they helped kill his father and fought on Scar's side I doubt he'll be very fond of them, and wasn't it said in Simba's Pride that all the hyenas ran off or did I miss-hear?
And wouldn't what is really two prides (Pridelanders and the Outsiders) be able to beat one? Unless it's a supersized pride for some reason, which if we do do this would need explaining. If it's just a regular pride pretty sure the united prides will handle it just fine.
It seems kinda too soon to do something like this anyway, Kopa just returned and the family still needs to get over the shock of it all, Kopa still needs to settle back in and catch up with his parents, meet Kiara etc.
And then there will be the problem with having to strip the rights of inheriting the kingdom from Kiara and Kovu since by default, Kopa is the rightful heir. It would be best to get that out the way first before having something like that.
Not saying no to a rival pride all together, it's just way too soon and it needs to be more thought out between the group, we would need a reason for the Prides to be rivals enough for the other to try and invade.
Some RPS do have a Skype chat to discuss their RP in, it's helpful since everyone can discuss something at the same time without waiting for a forum reply, we could try that, unless one of us don't have a Skype account then that may be a problem.
Just think it will be easier to discuss what happens in the RP as a group like that, communication between members is as important for a successful RP as the plot is, without communication half the time people won't know what's going on or what they are met to be doing.
But hey, I'm not in charge here so who am I to say.