I'm about to try to catch Heatran. any tips?
Bring 25 Dusk Balls(yeah, do it at night again), as well as a bunch of Ultra Balls just in case. It took me 4 dusk balls, but I may have been lucky.
Do the catching at night for a 4x catch rate w/ dusk balls, and either put it to sleep or paralyze it(sleep being better if you can).
Weaken it and try to get a False Swipe in if you can, although being part steel you'll have to have your Swipe user at a pretty high level.
If it woke up(if you put it to sleep first), then put it back to sleep and start throwing Dusk Balls.
Yeah, not much, mostly the same stuff for Uxie and Azelf, although the typing is different.