I have absolutely zero proof that I'm good at any of the games I'm about to list due to me being a retro gamer and kind of turned off by online. The few games I've played online, I've either faced someone incredibly cheap or had terrible lag (the only exception to this is Halo, but while I don't suck, I'm normally one of the lowest ranking players unless it's like Flood/infection or anything gametype which name escapes me). But anyway, off the top of my head . . .
Donkey Kong Country (the first one only, kinda suck at 2 and only okay one the third)
Super Smash Bros. Brawl (Melee maybe)
Dragon Ball Z games (Budokai 3; Budokai Tenkaichi 2; Budokai Tenkaichi 3; & Sagas [side-note: it's impossible not to be good at Sagas, terrible game])
Sonic Games (Sonic the Hedgehog 2; Sonic Adventure; Sonic Adventure 2; Sonic Heroes; & Sonic Generations)
Mighty Morphin Power Rangers: The Movie (Genesis; fun note, I hate this game. But I had to keep playing it because my brother was obsessed with getting a higher score than me. I retired without him ever achieving that)
RPG games (Xenosaga I-III; Final Fantasy Tactics; Disgaea IV; Super Mario RPG; Paper Mario [one])
Mario Kart series (64; Double Dash!!; & DS)
Super Mario World (The other Mario games, not so much. 3 being a possible exception)
Most of the 8 games on Kirby Super Star
Playstation All-Stars Battle Royale (as a rule of thumb, if I got platinum I'm mentioning it [unless it's a collection])
All Lego games I've played (all Star Wars ones & Batman 2)
Yoshi's Island
Soul Calibur III (Definitely not the same with V. That's another online exception I forgot to mention above, I won like three fights and lost like ten so . . .)
Wrestling Games (Day Of Reckoning series; Here Comes The Pain; WWE '12 & '13 [note: these are the main series I thought about with online, either laggy as fuck or cheap as fuck]; Smackdown Vs. Raw 07 - 11 pretty much, perhaps 06 as well but I lose there more than any of the aforementioned games)
& I think that's it, at least off the top of my head. I could've also put games like Animal Crossing but yeah, it's Animal Crossing didn't seem right listing it. For similar reasons, I didn't list any Mario Party games.