I hate DLC. HATE. You should just offer the full game for a price. Much better tactic IMO.
It depends on the game. I personaly prefer buying once, though it would be interesting to see this implemented. I'm thinking people would need to love the gameplay to want to upgrade or buy new features.
It's going to depend on the quality and playability of the game. whereas there'd be more lee way for non DLC games interms of quality IMO.
Also you'd have to monitor hacks and all that BS.
If you've got a plan figured then go with it, but I think non DLC is more solid, complete and less Hassle!
If the game is liked then you could have optional DLC characters for pro's but I think most of your players will be noobs/average and wont care about upgrades (especially if they
have to), until they get tired of the game.. and thats when you release Gaurdian Spirit 2

(Just like MK & the rest)
I know you're Pichachu and want to make it like Pokemon but you'll need a TV show, Trading cards and so on, you dont have any of that right now.
IM
HO
Thats my 20cents