1. Japanese Pokémon Web Moltres. This Moltres artwork is my favorite of all existing Pokémon TCG cards. I have a small collection dedicated to it. I can still remember receiving the Moltres and Zapdos at the cinemas (and my little brother had the Moltres and Arituno). From that moment I already loved the artwork, and over the years the nostalgia only added to it. The red and yellow, with dark volcano background is just beautiful. When someone mentioned the Japanese Pokémon Web set contained a Holofoil version of this artwork, I immediately bought this PSA-10 below, which was the start of my little collection of this Moltres artwork in all raw variations/languages; all sealed; and high graded copies for the English/Japanese ones.
2. Pikachu Emotions Japanese Art Academy card. My second favorite card is unfortunately one I don’t own yet. As a Pikachu collector I love this artwork for well… all the different Pikachu emotions displayed on a single card. It’s so well done. Both cute, funny and cool at the same time. I really hope I one day have the chance to add this card to my collection.
3. English Ghost/Phantom stamp Base Set Pikachu. As a Pikachu collector, I of course love the Base Set for its many different and unique variants. I like the Ghost/Phantom stamp version especially, because it’s unique to this card, and really represents what kind of weird misprints can be out there. At the same time it gives some insight in the printing process for the 2D vs 3D 1st edition stamps. Overall I love this card, and although there are rarer Base Set Pikachu variations out there, this one is among my favorites and those others aren’t. 
4. Japanese unlimited edition World Champions Pack Seviper. Seviper is my favorite Pokémon, and although I started collecting Pikachu in all languages and variations when I came back 5.5 years ago, I later on also decided to have a similar collection for my favorite Pokémon. In the end it took me 3.5 years to finish this collection, of which mostly this single card was the final hard to find one. But, because it was so hard, the accomplishment of finally finding it made me appreciate it that much more. After this Japanese card in unlimited edition arrived safe and sounds last month, it was just waiting for the two already incoming Indonesian Seviper cards, which arrived past Monday. It feels amazing to finally have completed this collection 100% complete across all languages and variations. 
The fifth one was a bit more difficult to pinpoint to a single card. So instead, the fifth place is a shared spot for three cards in no particular order:
5. Japanese July 18th, 2011 Teach Set Pikachu.
5. English MATCHPRINT Expedition Base Set Pikachu.
5. Japanese 095/SM-P The Masked Royal Promo in PSA-10.
The Teach/Tryout Sets are very unique cards, which were distributed to learn kids about the TCG in Japan. The sets from 2011 also feature unique artworks that aren’t used on any other Pokémon TCG cards, and this Pikachu card in particular is a very solid artwork that I love owning.
The MATCHPRINT Pikachu is probably the rarest Pikachu card I own. Only two copies of these were made, so I’m very privileged and honored to have it in my Pikachu collection. The MATCHPRINT cards were color proof test print for the Expedition Base Set, which were leaked from the factory by an ex WotC employee, who sold them to Rusty (TCA Gaming). After I had heard he broke up his set by selling his Charizard cards, I made him a similar offer for the Pikachu which I’m glad to say he accepted. And in addition to being such an amazing two of a kind card, it also has the Expedition Base Set Pikachu artwork, which is among my favorites of all Pikachu artworks.
The Masked Royal is limited to 100 copies (plus a few extras) in Japanese (and 28 copies in Korean). I collect Full Art Supporter cards in English, and also included all Japanese exclusive versions, like this card. This collection of mine is my absolute favorite to browse through and look at. The artworks of all of these are amazing, and if I would ever be forced to be in a position to choose between stopping my Pikachu collection or FA Supporter collection (I’m going to assume that won’t happen, but in theory), I would continue with my FA Supporter collection. It may be easier to collect, since it’s primarily keeping up with new releases, but I just love how this entire collection looks as a whole. And although The Masked Royal isn’t my favorite artwork among them, it’s by far the rarest and the center piece, especially being PSA-10.