There's this problem I'm having since getting the game, and I'd prefer you refrain from giving smart-alecky replies.
Every since playing the online mode, I find myself getting butthurt and hating myself after most losses for these reasons:
- Projectile spamming speedsters who are untouchable 90% of the time.
- Swordies in general.
- Any time I try out a character lighter than Ridley/Belmont, my win rate drops considerably, and after a few losses, I drop the character and never touch them again, preventing me from branching out.
- Taking only 1 stock or none at all while I get curb-stomped.
It's the reason why I only use the heavier characters, put tons of importance on winning, and the game stops being fun. How can I drop this toxic mindset and having fun again?
I think perhaps it's less about projectile spamming speedsters, sword characters, &c., and more about how you think of yourself. Step back from the game and ask yourself why losing affects your self-esteem. Do you already have a poor self-image of yourself? Are you afraid of losing? If so, why? Are you no longer enjoying the game? If so, realize that it's just a game. You can be serious about the game, but if you're not having fun, you're not going to do as well as you could. After playing the game and turning it off, do you experience a lack of desire or perhaps fear of losing when you play the next day?
There are two aspects in playing a fighting game that are hidden in plain sight. First, losing will happen. It's inevitable. Second, losing opens the opportunity to learn from your mistakes. If you accept your loss and treat it as a learning experience instead, you will gain more from that than you would from giving up or feeling demoralized. By the way, if you feel demoralized, take a break. If you play while demoralized, you might play poorly, which will only contribute in you picking up bad habits, and thus create a vicious cycle.
I think perhaps that because you play as Donkey Kong, you rely heavily on his weight to get you by. By playing as a middleweight or lightweight character, you can't rely on that anymore. When you find yourself losing again and again with a different character who is lighter than Ridley or the Belmonts, you give up. Back during the SSBB days, I wanted to try out Zero Suit Samus, but her short hop seemed like a full hop. It wasn't until SSB4 that I wanted to use ZSS because I wanted a character who could deal with those Samus couldn't, as well have the full Metroid experience.
I tried her, was dissatisfied, and went with Mario. Mario felt right, even good, but he also felt basic. I tried Sheik, who was technical and good. But it was between these three characters that I stuck with ZSS eventually. I couldn't just give up on her the moment I felt like I wasn't playing properly with her. Obviously, I wasn't going to win most matches, especially against my brother. I stuck with ZSS for my secondary, though. My brother saw me performing a lot better with her than before. Even my brother wants to have a secondary, but the moment he loses, he just sticks with his main. I think this is what's happening with you.
Rather than picking up a new character who may be lighter compared to Ridley or the Belmonts, you give up when you're not seeing any results. Focus on learning how to use the character and what he or she can do. If you focus on the results from the onset, you're not going to perform very well with that character. There's a saying I just recalled from the TV show, Smallville. Jonathan Kent, the adoptive father of Clark Kent, said to Clark, "You can quit if you want, but remember: quitting's a very hard habit to break." I'd say give a week of trying out other characters. Find at least a character who feels right to you who isn't a heavy.
In my signature is a link to a thread I made some time ago. It received a lot of likes early on and even today, I still receive likes from others on this site. If you're interested, feel free to read it. I hope it'll help you develop a growth mindset and help you not to be so hard on yourself. I know from experience back in SSBB what it's like to be demoralized, to not have fun after losing over and over again. Also, if this mentality or attitude you have stems from something else not related to SSBU, but SSBU is causing it to manifest, I'd encourage you to speak to someone you trust about any issues you might have. I hope you succeed in your future matches. A positive mindset and the right strategies will get you far.