As part of moving onto V3 we're starting from fresh with the archives especially due to a few rarity changes, so the best way to include the older cats I figured would be to set up a transfer page. All you need to do is post the link to the oekaki with your cat(s)! ^^
Then me or one of our other members will look at your cat, quote your post with the updated traits - if you haven't had your traits updated within 7 days of posting feel free to pm me
If you don't wish to transfer your cats over that's okay, you won't lose your character however they won't be official Shadow Cats any longer
There are no time limits to this either, cats can be transferred over at any time