I started collecting Pokémon cards at age 7 after seeing the cartoon on TV. I’ve never played the Pokémon TCG and also never tried to learn it. In fact, @pfm explained most of the rules to me while we were watching matches at Worlds 2022 in London. 
MTG I never collected nor played, and none of my friends did either. I usually saw older kids play it at high school and college.
Nowadays I keep gifted MTG cards that come with Pokémon orders, but that’s about it.
As for Yu-Gi-Oh, me and my little brother were gifted a collection from a friend of my little brother. At the time I was 9 or 10 years old and could barely read English, so we made up rules ourselves (I guess that more closely resembled the cartoon games than the actual Yu-Gi-Oh! TCG, haha 
). When I was about 14 or 15 years old I started playing Yu-Gi-Oh online and my little brother quickly followed suit, and after that I’ve bought quite a few cards to make my favorite online decks irl (usually slightly adjusted with only affordable cards), even though I only had my little brother to play against irl. After a few years I had like 10-15 different decks. Some I remember out of the top of my head: Zombies Xyz; Naturia Syncho Lock; Crystal Beasts; Final Countdown; D.D. Inferno Golem; Reptile; Spell Counter; Batterman; WATER.
I never played competitive, only with my little brother for fun, until he stopped collecting/playing.
I also remember doubting about buying a Secret Rare Black Rose Dragon for 35 USD for about 2.5 weeks, before I finally bought it. Oh, how times have changed.
I used to buy Yu-Gi-Oh cards from gametimecc.com for years. But after a while there were more and more cards on my wanted list that were never in stock, so I started looking for an alternative and came across TrollAndToad.com. Unlike GameTimeCC, which is primarily focused on Yu-Gi-Oh, TnT also had a lot of Pokémon stuff, so I also bought a cheap Venusaur and Hitmonlee with one of my many Yu-GI-Oh orders (the only two gen 1 Pokémon cards I didn’t have as a kid).
And eventually I placed all cheap Pikachu in my TnT basket on impulse back in 2015, which was basically the start of my Pikachu collection. Soon after I only collected Pokémon cards and quit collecting and playing Yu-Gi-Oh, until some of my Pokémon goals were complete or almost complete and I decided to collect one of each Yu-Gi-Oh rarity, including all variations, OCG/Korean, and misprints, for which I’ve actually written an article here on the forum:
I still add to this collection, but not actively. If I notice a new set contains a new rarity through a randomly suggested YT video, I buy a single in that rarity once prices drop a bit, but I haven’t searched for any of the misprinted rarities I’m missing in a long while.
TL;DR: Pokémon TCG was for collecting; I’ve never played nor knew the rules. Yu-Gi-Oh TCG was for playing. (MTG TCG neither.)
For the TCG, the main different between MTG/Yu-Gi-Oh and Pokémon, is that the former were 100% focused on TCG players (they have started focusing more on collectors in the last 2-3 years though, but for the two decades prior barely), whereas Pokémon was focused on both collectors and players 50-50. I also feel like the Pokémon cartoon/anime is much more kids-friendly compared to Yu-GI-Oh. And even though I liked to watch both as a kid, I’ve watched every single Pokémon episode/movie (yes, over 1200 episodes and 25 movies…). Whereas for Yu-Gi-Oh, I’ve only watched season 0; the two seasons with Yugi; and the two movies with Yugi. Since I watch anime pretty regularly, I’ll probably continue watching the other Yu-Gi-Oh seasons eventually, but not sure when.
Greetz,
Quuador