I recently went through and updated up my 151 frame to be as uniform as possible

Here was the criteria I aimed to meet:

1. All cards are only from Base set, Jungle, or Fossil (except for Mew which only came from a promo)

2. All cards are shadowed, no shadowless versions

3. All cards are unlimited edition, no 1st editions (except Base set Machamp which only ever came printed with the 1st edition stamp)

4. All cards have the 1999 copyright, no 1999-2000 copyrights

5. If a Base set card has an additional variant in Jungle or Fossil, the Base set variant is used