Thinking that Focus Sash was reusable in DP, back then, I had really noob 4 attacking mons and it was a miracle to get past 21 in the Battle Tower. So, after spending 48 painstakingly earnt BPs to buy the Sash, and equipping it on Torterra, I switched my "sashed" Torterra to Cynthia's Milotic, and taking an Ice Beam with 1HP. Ha, beat that Cynthia! So, after beating her and the game autosaved/ credit rolls, I checked my team again.
I remember playing Silver when I was younger and all was going well until I entered Mt. Mortar without a Pokemon which could learn Flash. Pitch darkness. No Escape Rope. I made the mistake of saving and forgetting about it for a little bit and my Silver character never escaped Mt. Mortar. Eventually the internal battery of the game died. As did my character.
I remember now though that I had painstakingly caught an Abra.
Which knew Teleport.
This has already been mentioned, but when I was younger I would always train up my Togepi on Chrystal with Metronome as its only attacking move. It would always use Selfdestruct or Explosion when I hadn't saved the game in ages ;-;
Mine probably was when I was playing Platinum, I come across a shiny Fearow legit. I had my Action Replay in at the time even though I wasn't using a shiny glitch, so i threw one of my 999 masterballs at it. I caught it, I was super happy since it looked like Ho-Oh, then I bumped my game and my super flimsy AR came out and I lost my precious baby o-o
I was on the phone with a friend at the time and I literally chucked the phone and my DSi at the wall.
I made the mistake of lending my ruby cartridge to a "friend" with strict instructions not to touch the things in "box whatever"
Of course, when I got the game back, "box whatever" was filled with Zigzagoon all with swear words for nicknames, and my lv100 Groudon and my shiny Graveller were both gone forever.
I haven't spoken to him since.
Pretty much stopped with pokemon then until DP came out.
In contrast to most others in this thread, on Fire Red I gave my masterball to a pokemon so I didn't accidentally use it on something crap.
At the time, I thought I had to use it on Mewtwo, so when it wasn't in my bag, I panicked and reset the game many times, only to realise the pokemon that had the masterball was in my party all along.
I keep getting Haunters over wondertrade, then picking the best Gengar to keep and wondertrading the rest.
I keep panicking that I've just wondertraded my Gengarite, luckily not yet, but I can't help but think it's going to, one of these days...
And the number of times I've used Rare Candies on a pokemon that's only like 10 points away from levelling...
Recently in BM I nearly lost becuase I had Garchomp v Magnezone. first turn was EQ which activated sturdy, then it magnet rised. The problem was I didn't notice and kept mashing A while doing other things. Thankfully RNG gods blessed me and let my chomp survive with 3 HP, avoiding the 2HKO and the beeping alerted me that it wasn't gone yet. I laughed awkwardly
Both of mine were Gen. II related, so I was about 8 or 9.
Silver: I got lost in Dark Cave without Flash. I thought my game froze and I'd never get out, when in hindsight, I was probably right next to the entrance. I had a level 20-something Bayleef…
Crystal: My very first (non-Red Gyarados) shiny was a Blue Ditto by the Pokémon Daycare. I didn't realize until years later what I'd encountered. I thought at the time that my screen was broken on the inside or that my game was glitched so I ran away.
And now I've run into a Gold Geodude and a Green Hoppip, both in X version… SMH
Not exactly sure which gen I was playing in, but boy howdy did I waste a lot of time, I believe it was Gen 4, Pearl. x.x
Here's what happened:
After beating the game, I wanted to make the most awesome team I could. So I bred the best mons I could think of (this of course had not taken IVs and Natures into consideration, or type coverage for that matter), and taught them all the best covering moves I could (A whole team of nothing but attacks, no status moves or anything, and only ONE egg moves). Then I went throught the elite four about 50 or so times to get enough money to buy 51 stat boosting items for each Pokemon, because I thought their stat growth was based on some magical formula (I had no idea...) and if I gave them as many vitamins as I could, they would be the most powerful Pokemon ever!
My team had Ursaring, Zangoose (pre-Toxic Boost...), Scissor (I actually bred Silver Wind onto him... and taught him Metal Claw, Swords Dance, and Some other special move), Absol, Aggron, and Lucario (Mixed Lucario...).
I had no idea what I was doing. I still have them, and occasionally look at them as a reminder of my humble first steps into competitive Pokemon.
Yesterday I was just lazily hunting in the friend safari for a shiny drought ninetales (since it's my favourite poke of course!) and didn't realize I had run into a shiny magmar until I had already hit the run button! :( this has happened at least 3-4 times where I accidentally run from a shiny. Zzz
I also remember one time when I was little challenging the e4 for the first time and failing over and over again until I finally got to father than I ever had before... Only to lose to gyarados because I could not for the life of me figure out what type it was.
So lately I have been trying to SR Moltres, so I had just finished capturing and went to check it's IVs, I also was going to trade with someone today. I connected to the internet but said person was not on so I check Moltres and decide it was not a keeper, so I reset. Only then did I realize I saved when I connected to the internet and now I'm stuck with this shitty Moltres until pokebank comes out and I can restart my file >.>
The other facepalm worthy thing I did in Pokémon was after I sold a valuable item; I just assumed there was nowhere else in the game to get another one and dealt with it for 3 months before Lucariomaster2 told me there was another.
I did a recent facepalm-worthy move.
I was horde EV training my Alakazam in the breeding route (the 1 with horde Psyduck, Roselia, and Hoppip). I would slay all the Psyduck and Roselia hordes I come across. As for the Hoppips, I thought they'd give speed since I was thinking of Jumpluff's best stat being speed, so I killed them as well thinking that Hoppip gave speed EV's.
Later when I checked, I was wondering how'd I get so many sp def EVs.
I spent the next day growing Grepa berries when I discovered my error.
Apparently you can't give away the mega stones (or the lucarioite at least) via wonder trade, so that's... saved me a few times.
I had my red card equipped to my mienshao. I went to challenge the elite four and halfway though he used it and I lost it. I've did the same things with flying gems (also with mienshao).
Also, one time I was down to mienshao vs dragonite. I assumed it was water-dragon, and used hi-jump-kick on it before I remembered it was part flying! Turned out it was a zoroark in disguise, so it worked out XD
And I remember the time I was trying to catch a shiny deerling. I assumed it had a low catch ratio so I cut it's heath by half and threw a premier ball. It jiggled but broke out at the last minute then used jump kick. It missed. It died.
I still kick myself for not using an ultra ball...
When I was younger, me and my brother both wanted to add dark-type to our pokemon TCG. I was really excited my brother got a dark-type energy card, I traded my all-type energy card for it...
When trying to get to Mesprit, I kept flying to the nearest location. Needless to say, it was at the other end of the region (Diamond, also my first game).
Also, forgetting to save after 48 hours of gameplay (not in one go, but over two days). It sucks.