Yes the battle tower is full of powerful 15 dv's pokemon that have had the PC trcik done to them ALOT. Basically they have max stats for there level meaning you need some seriously strong pokemon and luck. I just through a load of ubers in (I don't do this in competitive battling but here you have no choice). I only really battle in the lv:100's. I use Mewtwo, Lugia and Charizard (I don't have ho-oh on crystal). I still don't win all the time it's about 50 odd percent mabye a bit higher. Hope I helped.

PS: Always have aeroblast on lugia and amnesia on mewtwo (to survive).