1. It would have helped to know that by beating the inital campaign that it would reset all your link levels (except stored in gallery for use in wifi battles). I woulda spent the extra time to get things to evolve so they stay their evolved form when you reacquire warriors in the episodes.
2. It resets your items and money too, except for a few specific items, like evolution items and guardian charm. Oh, and junk from failed item creations, for some reason.
3. When the rare trader pops up, spend all your money on guardian charms and evo items. He doesn't pop up often. Also, the guardian charms will let you run a pokemon solo through a territory and juggernaut through it, allowing it to nab lots and lots of link % increase.
4. Wishing I knew that you CAN recruit the special warlords in campaign. You just have to beat them under the usual recruit techniques except you have to finish 'em off with your hero's pokemon. Which is friggin' hard to do at first because evee pretty much sucks after the first 4 territories and while you could use a thunderstone and get a badass jolteon, i had to wait to link level 70 for an umbreon. Good thing you can link with something else and raise that to defeat stuff if you don't want to wait.
5. You really have to reconsider evolving to the 3 evolutionary stage for a lot of pokemon. They become more powerful, but they can move far few spaces in a turn. Which also sucks for things like ampharos that uses thunder and you have to be a specific distance from your foe. So the middle evolution with discharge that hits all around you is better.
6. Gyarados is a beast. It can fly over all the things, hit a good row for ko'ing multiple foes at once, and has a knockback effect to knock bitches into damaging stage areas or off the flags you need to capture but they're tanking on it (flag regens some health each turn). Similar but not quite as good is dragonair. Also, dragonair>dragonite.