Most similar character between Brawl and Ultimate [closed]

Given your response to the comments, I would say the answer is "whoever you feel most interested/comfortable with". Most characters are very similar or only have a few new moves, so for just learning the basics of Smash any character should be ok.

A lot of skills are transferable between these two games, even if the details of general mechanics differ quite a lot. There are major differences in some specific situations, but I doubt they will come across as important unless you're relatively experienced in Smash.

Some characters have more substantial changes between Brawl and Ultimate, mostly due to reworks done in Smash 4. These include for example Link, Diddy Kong, Zelda, Meta Knight, Falco, Yoshi, Ice Climbers, Sonic, Bowser, R.O.B., and Olimar.

For learning the game I also don't have any specific recommendation. Each character has its strengths and weaknesses, and you'll find out about them as you improve. Some people feel that characters with multiple mid-air jumps are easier to control at first, but it's ultimately down to preference.

Combos are quite different between Brawl and Ultimate, but outside of tournament play they rarely are the deciding factor of matches.