UBI Soft, as so far they are the only ones that have provided exclusives or limited time ones to both the Wii U and the Switch. Granted recently most have had Nintendo IP attached but they have done more then most. Bandai Namco have been ok but mostly with late ports or retro stuff.

My answer to this question changes depending on exactly what time period were talking about.

But, generally speaking, I'd say Sega. Sega has been releasing games on Nintendo platforms continuously since their exit from the hardware business.

Well, if were talking about the Switch generation, I think I'm going with Bethesda. They're the only western publisher putting recent, mulitplat AAA games on the platform.

When it comes to quanity square but for ambition Bethesda or Ubisoft

For me it is Sega. I really love Puyo Puyo Tetris, and now I know I will get both Sonic Mania and Valkyria Chronicles 4 in the future.

I would say Ubisoft because Mario Rabbids and StarFox in Starlink had a big impact in terms of reveal. And everyone seemed to be happy with it.

I would say Platium Games. They have been very supportive for Nintendo for awhile now and there games have made huge impacts.

Plus Games like Wonderful 101 which i throught was great.

i would say EA because of the unprecedented partnership

Ubisoft - Mario + Rabbids (great game with great DLC) and StarFox in Starlink

Bandai Namco is also notable if they realy working on Metroid Prime 4.