I personally tend to check smogon for this sort of thing, however let me make an attempt
lanturn his honestly not that great when looking at both its stats and its move pool so you might be better of simply dropping it, for gardevoirI would suggest either a timid or a modest nature paired with moon blast, shadow ball, psychic and magical leaf.
for arcenine you can go both ways with attack and special attack seeing as the stats doesn't have such a big gap between them so the nature should complement either or both, as for a moveset I would suggest flare blitz, extreme speed, morning sun and perhaps fire fang.
and lsat for Lucario: either an adament or a jolly nature paired with close combat, bone rush , metal claw and extreme speed.
I hope this helps you find a general direction.