>>21994855DexNav level doesnt get you better stuff. Higher chains do.
Chains are hard-ish to break at least, so long as you dont leave the area or run away. even if another pokemon pops up while youre using the search function, you can carry your chain further. The best way to keep track is to gauge levels; They should spike every 5 battles, and steadily climb otherwise. So like 14, 14, 15, 16, 24, 17, 18, 19, 19, 29, 20, 21....
In addition, hgiher chains will net you better IVs and egg moves, but Potential is still pretty random
