I recommend Mewtwo and Ho-Oh because they are both Lv. 70 and any lv. 75 and up.I will give a Lugia or Ho-Oh Lv. 100 for a shiny eevee put it on gts.
The elite four
Lv 42 to lv 45
Yes. If yu beat them 1ce, they get Level 65-80 strong
train your pokemon up to level 80,90, or 100 and teach it TMs and HMs
For me, I trained in Victory road and the grass around it. Make sure your Pokemon are AT LEAST level 40 or higher, bring at least 30 hyper potions. I beat the elite 4 when my Pokemon was at level 40-45.
In Soul Silver, ironically, the strongest level Pokemon you can find there is a Level 70 Ho-Oh. Don't forget that the Elite Four up their levels each time you defeat them.
Suicune is at Level 40 in HeartGold and SoulSilver.
You should train your Pokemon over level 50 and teach it good moves. The elite four are actually quite easy but Lance is your toughest guy to beat.
By training your Pokemon.
You can trade from diamond, pearl, or platinum You can also beat the elite 4 and get ralts through a swarm and evolve it at level 20
breed it
lugia is level 45.