[quote name='sterlingice']I'm not looking to go nuts grabbing all 30 characters but just play with the 3 starters. Is there a difference between experience there on different systems?[/QUOTE]
The 3DS is completely different. It is a single player jumping platformer. Your character levels are all that matter, you gain abilities and more hp by leveling and the level number is all that transfers over. There is a "daily bonus" of experience for finishing a level using a Skylander of one of the two selected elements of the day, you can tell which two it is by the circle at the starting point. It is a lot of fun, but only if you don't mind jumping games. There are crystals that you gather for earning achievements during the levels, like "don't eat food" or "gather XX totems", etc. There are two types of levels, basic get to the end type levels, and challenges where you have to fight in an arena like setting, both types have 5 crystals to gather in various ways. There are 5 hubs, each of a different environment type (ice, forest, etc), each has 3 "get to the end" and 2 "arena" levels. You have to play through each several times to get all of the crystals (although you can earn multiple in 1 trip, it is impossible to do it in less than 2 trips). The last level is a combination of the two types in a single level. Adventure packs open 1 new arena and 1 new scrolling level, with a completely new type of environment (not retreads of the others). Skylanders have different abilities, more self sufficient in nature.
The Wii/PS3/360 version can be most closely compared to a streamlined Diablo. The Wii was the lead platform, but the graphics are a bit sharper on the PS3/360. The Wii version seems to run a bit more smoothly at the cost of lower def, and uses waggling of the remote (the other two just the right stick). You have character levels (which increase hitpoints), abilities (which you buy with gold you collect), a branching skill tree you can choose for each character to focus on one of two specific abilities and special skills for each path, and stats which can be raised by finding hats or doing challenge levels. Normal levels are Diablo type levels, with story points, an occasional puzzle or target shooting section, a few secret items (hats, story scrolls or locked upgrades for each of the 37 characters), and a boss type encounter on some levels. There are 22 standard levels and they are themed, usually two or three levels per theme. The adventure packs unlock 1 new level each using variations on existing themes, but the objectives tend to be a lot different (like world shifting between ghost and real world for Darklight Crypt) and they are quite a bit longer than standard levels. There are some hub level puzzles, as well as access to NPCs that give you access to upgrades/challenge levels/etc. Each Skylander unlocks a challenge level that can be played by any character to augment your stats. Those are single player levels that are usually things like kill XX monsters in XX seconds, or find XX items, etc. You also have player versus player arenas that are a blast, adventure packs open one new arena each.
If you have both the 3DS and a console version you can unlock adventure packs in both. Skylanders can be shared, but only levels transfer into the 3DS since it doesn't use gold. You don't lose gold, it just doesn't show up or do anything in that version - but it will still be there when you go back to console. It is much faster to level in the 3DS, but all that will give you is more HP in the console version - you still have to buy skills. The same hats exist in both versions (and can be earned in either) but do nothing more than looks in the 3DS.
Characters are very different from one another (except for the Legendary/Dark version of others), not simply skins. It takes some practice to get the hang of some of them, but ALL of them have value in certain situations (not essential, but they make certain tasks easier). The console version is great in two player, because some characters are fairly weak solo, but complete monsters when paired with other types. For example Prism Break alone is challenging, but paired with a melee like Chop Chop you can shred legions of enemies.
Stats are stored automatically on console, if you move the character the game pauses until you put it (or another one) back. In the 3DS, you load two in and you have them till you go back to the guy to replace them. You have to reload the same character to "save" earned levels back on the 3DS. If you level a character on the 3DS, then go and play it on console, the level transfers back, but if for some reason the level is out of sync from what you had last time you played the 3DS and when you try to load it again it will assume the higher of the two values. The console takes what is saved as the level. In other words, your 3DS remembers the highest level you have achieved in that version for that character. The console version just knows which ones you have loaded before on the collection list, you can have duplicate of Gil Grunt at level 4, 6 and 8, and loading each will be that level. If Gil Grunt is 8 in the 3DS and you load a level 4 one Gil Grunt will be level 8.
All in all, the games complement each other well, I personally feel it's not an either/or choice. And having both means every character and adventure pack expands TWO games instead of one.