I didn't mean to make a big post here, but it turned into a story time post
Well, I choose characters based on favorites pretty much lol. I chose Mario and never got a secondary in 64,melee and brawl cuz no one clicked with me as a char and I didn't particularly love any of them the same as Mario. Then smash 4 came out, and I tried mega and my god he did not feel right. at all. So I went a good 6 or 7 months just maining mario, toyed with rosa/zamus but they fell off for me, since I wasn't super enthralled with them and I figured any time i spent on them would just be hurting my marios growth.
I did toy with mega here and there as a handicap cuz of how completely unorthodox he is compared to Mario a lil bit but it was bad(i'd dair into the ground and downsmash as a quick punish[Mario habits X.X]) One day i was talking about how some matchups seemed really hard for me(Luigi and Diddy in particular, Rosa but not quite as bad) with my friend and he told me I needed a secondary. I explained my reasoning on secondaries taking practice away from your main, and he said i should pick something good for those chars I'm bad at. I took exactly half of his advice.
I ended up deciding if I was going to get a secondary it's going to be a character I thought is awesome, and not just for countering problem matchups. Megaman is this character for both that, as I reasoned If you have a secondary, you want something significantly different than what your main offers. Mario and Mega are both very different(though my hyper aggression still somehow bleeds into a defensive character.
Thus, I spent a ton of time learning mega and reading information. I don't find mega exhausting myself, he feels like a breath of fresh air with how different he is for me(the fact that he has so many options means there's always some trick or fake out I could learn that i'm either not aware of or not using enough). It prob helps that I feel Mario is heavy on just fundamentals and very light on technical requirements though, given Megaman has all of the technical requirements to learn lol.