Giovanni is awesome. But then again, that opinion seems to be decently popular in this thread, so...
The way Missingno was handled was, to put it simply, godawful. Personally, I want Missingno back in Gen 7, with a full evolution. Not a mega, just an evolution. Also, the way a lot of the fandom handles it is disgraceful (
I'M LOOKING AT YOU, LINKIRA). As for how I think it should have been handled? Well, just for a taste of how it could have been, if a bit meta for my taste, can be found at
http://www.thepokemontower.com/authors/missingno.shtml, in "A Lone Missingno.", which was pretty much my childhood. Warning: May be 2awesome4u
Ever heard of Marin? You didn't? Well, Marin was fan-made and won a contest to design, and I quote, "Pikachu's Friend". Also, it looks adorable and ALSO needs to be in Gen 7.
The entire Pikachu family deserves better. As in, "Make Pikachu stronger than its clones and Raichu even stronger, probably at 445 and 550 BST respectively" better. I mean seriously, the mascot needs a serious buff.
Tynamo is adorable and deserves a cuter evolution. Maybe a branch evo?
List of signature moves that need to be better,
Freeze Shock,
Ice Burn, Oblivion Wing, Volt Tackle, Bonemerang,
Shadow Force, and
Roar of Time. None of them are that great, and the bold moves are completely unusable.
Back to actual opinions, the games with Shadow Pokémon are excellent, and we need an updated one for Gen 6 or Gen 7.
Really, none of the games are bad (except Channel). Gen 5 still wasn't great, though.