I haven't played much of the 3DS version outside of the demo, but I feel like it would be hard to transfer your skills over to the Wii U version just because the control schemes are so much different; unless you play with your 3DS on the WIi U...I have yet to see how my meh in person 3ds abilities translates to wii u in person! None of the experiences against friends were good lol
I only played against one on wii u (online). I lost all 20 sometime games. It got to the point where he was just trying out the dlc characters as this was after EVO. This friend is not in the community, but his cousins were back during melee. He's probably the most likely to help me but doesn't have time due to terrible work schedules.
Another friend that I know through my best friend, I just played online on 3ds (right before wii u came out). After a dozen or so losses, I think he just would go Ike to give me a freebie, which didn't happen He's on the other side of the country and occasionally attends tournaments.
My "best" friend, who happens to be semi relevant, would play me throughout October/November in person. I stopped bothering him to "train" me as it just became "lab sessions" for him. I even realized Diddy's up air was broken before he did (he would mainly combo dthrow>bair>bair). I think I may have won once somehow; he likely SD'd or got careless trying to practice setups. He's become "esports now" so doesnt have time for irl people or non smashers.
It's all good man. You just got to tough it out. It's hard to find players that are on the same level as you are on all the time, but there are a lot of things that you can learn from really good players. I got dumpstered by cero5 every single game; hell most games he 2 stocked me. If you're having trouble finding someone to train with you can always try Smashboards, Reddit, or even Anther's Ladder. Of course practicing in person is always the best!
Did you really want a dirty win though? Winning against someone sandbagging doesn't sound like it would be worthwhile.
I understand what you're talking about. I just kind of went through that lol. Diddy got nerfed a bit since then though so I don't think his combo is that crazy anymore. I don't know you and your friend personally so I won't say too much, but hopefully he'll play some friendlies with you sometime. It's good to remember that the game can be enjoyed casually also! 8)