Digging deeper into 1999 Base Set Pikachu.
Found that:
1. The font for Shadowless 1st edition, Shadowless, Shadowless CD Promotion Japanese is thinner, and they got a bit thicker in the shadow version;
2. The distance between the HP and the energy used to be farer away (for Shadowless);
3. When they made the Metal version in Celebrations Collection, they replicated the Shadow version instead of the Shadowless;
4. The HP is in red, rather than Black (unlike the 1996 Japanese Base Set);
5. The classical collection is designed more towards the 1996 Japanese Base Set, where the HP is in black, but still, no level.