Yeah, it's probably League if Nintendo talks to Tencent directly.
The other potential IP Tencent majority owns is Grinding Gear Games (Path of Exile). PoE is not in the conversation at all though, so not likely. That said,
kinda think it'd be fun to speculate about PoE: I just don't know where to start since I don't play that game.
Their most notable minority stake is Epic Games, but they do also have smaller (5 %) minority shares in Ubisoft and Activision-Blizzard, as well as 1,5 % in BlueHole (PUBG). They also recently got a 20 % share in Marvelous (Story of Seasons).
Tencent also has connections with Capcom (the mobile game Street Fighter Duel, which
TiMi develops), Konami (the mobile game Contra Return, again by TiMi) and Koei Tecmo (a
Dynasty Warriors mobile game, by you guessed it). No shares there (like with SNK), but they're nevertheless connections.
Yeah, they have a massive web of connections. The reliance on connections is a weakness of theirs - since they rely on them a lot of the time (more than most major corps do anyway) and they don't have a strong history of game development outside mobiles. The monetization freeze that the Chinese government / regime imposed in 2018 hurt Tencent
badly (at least $160 Billion lost during the freeze. Not kidding.) since they couldn't make money off of PUBG Mobile or other games.
I personally suspect that it was the freeze that lead Tencent to approach Nintendo in the first place - the freeze also exposed Tencent's lacking console presence.