My final team: Glalie (Fire/Water), Raichu (Fire/Ground), Golduck (Bug/Dragon), Pidgeot (Grass/Electric), Kingdra (Psychic), Blastoise (Ice/Poison).
It's Emerald, but different, since every single Pokemon out of the 386 has had changes to design, typing, and moveset. And yes, there's grass just about everywhere, even on some water routes and in the towns. And while the storyline isn't all that different, who really cares right? There's new regional forms and such and yes you can complete the whole Pokedex in one sitting! So for this hack, I did a ton, and I mean a ton, of research before even starting the whole thing, crafting my own spreadsheet in order to analyze the best possible Pokemon to use before I even played. I paid special attention to typings, abilities, and movesets in particular, and that culminated in what I had as my team above, plus a few other ones like Houndoom which were also useful.
It was also very nice to know how every trainer had differing teams (well, almost, the S.S. Tidal trainers were not changed), and the difficulty curve was honestly perfect, nothing too much in overleveling aside from Magikarps that some trainers have. Heck, on that topic, Magikarp is actually more annoying due to being a Poison Point Pokemon. There's a few other ones where the ability can totally mess you up. Mankey and Primeape are Ice type, yet they have Flash Fire. Tentacruel's typing should make it weak to Water but it has Water Absorb. Quite a few Pokemon have Fire or Ice weaknesses in typing, but also Thick Fat. Then there were Pokemon I just thought weren't all that great in the long run. The Hoenn starters were all mono-typed, and most Fighting types weren't as good as I expected. Some move changes at least made some moves more interesting, like Water Pulse being 90 base power and Rock Smash being 50 base power. There's a lot to take in and I looked back at my own spreadsheet constantly as I went along.
Furthermore, even though there's no Fairy type, I do like the workaround of making Poison strong against Dragon. It gives the normally not-so-good typing a better crutch with an extra type it's good against aside from Grass. Ice also got crutches with being resistant to Ground and Water, while Steel isn't resistant to Ghost and Dark (as it should be) and also Psychic as well. Anyways, the game sort of has some linearity to it, due to ledges being in place in certain areas preventing backtracking at times, but it's not so bad. Victory Road was a surprise with every gym leader and frontier brain battling you again. Emerald but with a twist. I dig it, especially since I haven't played a Hoenn-native game in a while.