I agree. Let me kick off the on-top conversations again! The reason why i haven't played my Omega Ruby game is because it is too hard to pick a starter now that all 3 of them have a mega and I had a blaziken on my pokemon X game. This means I am annoyed by the fact that I cannot choose a starter in ORAS.
Well you could set things up with someone so that they'd trade you the two other Starters. And while you can't get them until you defeat/capture Groudon/Kyogre, when you do on Route 114 you can buy the two starter's Mega Stone you didn't choose for 1,500 each (so 3,000 together). BTW don't buy the other 3 stones from the guy, they're just Hard Stones which you can easily get one for free by completing the Trick Master's 2nd Puzzle or just smashing rocks with Rock Smash.
But if you want to do things the intended way, here's how I would go about thinking:
1. Since you got the Event Torchic and used Mega Blaziken in X then you'd probably want to use another Starter, so that removes Torchic (it was the same deal for me, ORAS is the first game I didn't choose the Fire Starter since I used Mega Blaziken in my Y and wanted to try out one of the other Mega).
2. Since you have Omega Ruby you're going up against Team Magma who uses Numel and Camerupt. So if you want to make things
easier on yourself you can choose Mudkip and sweep through their teams no problem (as a bonus it also learns Rock- and Fighting-type moves to easily deal with their Zubat and Poochyena families). Also Mudkip has an advantage against 3 of the Gym Leaders (Roxanne, Wattson since by then it would be a Marshtomp and likely know a Ground-type move, & Flannery) & Steven and pretty much neutral against the rest (though having ways to deal with Norman, Winona, Sidney, and Glacia via those Rock- and Fighting-type moves it can learn).
If you want a
bit of a challenge and encouragement to use a variety of Pokemon you can pick Treecko (and while Treecko can also learn a few Rock- and Fighting-type moves its more of a Special Attacker plus its weak to the types Zubat and Koffing families are. Also if you choose Treecko DO NOT EVOLVE IT UNTIL YOU REACH LEVEL 21, that's when it learns Giga Drain and it's higher evolutions do not learn it so this is you're only time to get it). Not only that, but Treecko may also have an advantage against 3 of the Gym Leaders (Roxanne, Wattson, & Wallace) it has a disadvantage against to 2 Gym Leaders (Flannery & Winona), 2 Elite Four (Glacia & Drake; though if it Mega Evolves it'll be on par), and Steven (and on top of that isn't really versatile in ways to handle others super effectively).
I gotta be honest, I'm annoyed a bit by how soon XY and even to an extent ORAS at times gave you the means to use Mega Evolutions, as I do think those were a factor in complaints of difficulty being absent.
Everyone jokes about "welfare Lucario" in XY, but honestly, by the point you receive it it's not that bad relative to what the rest of your team should be by then. It's the Mega Stone they give it, considering even without competitive min-maxing, Lucario is an offensive bulldozer. And that's assuming you weren't using the Mega Stone for your Kanto starter (which also annoys me since it kind of overshadows your Kalos Starter Pokemon for the Mega Form). Not only that, but if your starter is Mega capable, it's likely to reinforce the "use one power-loaded mon for everything" philosophy since the Mega form only makes them even stronger.
I know you have the option not to use them, but being handed them tells me the game expects you to, and its difficulty really didn't account for that.
And a small, different matter is I don't like the ease of most of the Rival Battles, even since Gen 5. The point of the rival battles to me always felt like sort of a "beef gate", where if you can't beat them, even if just barely, you're not ready for the stuff that comes between then and the next battle.
Yeah, just getting the Kanto staters in general felt like the Kalos starters were being overshadowed. I'm hoping in XY2/Z they at least give the Kalos Starters a Mega Evolution (and maybe not give a second starter). But you're right that the game doesn't really account people using the Mega Stones, I can sort of understand why for those who don't but at the same time for those who do they're probably looking for a challenge.
I'm okay with the Gen 5 Rival battles since they happened often enough it felt that, though they weren't too difficult, they were keeping pace with the game's gradual difficulty increase. However not so much with Gen VI, despite having 4 Rivals there's a lack of Rival battles and when they did happen they didn't feel any more challenging than what you dealt with already.
Also, while answering the first question I came up with a
new annoyance: Aqua's & Magma's choice in Pokemon. Aqua you would imagine use Water-types and Magma would use Ground & Fire-types. So here are the Pokemon of those types in the Hoenn Dex:
Aqua: Lotad family, Goldeen family, Magikarp family, Marill family, Tentacool family, Carvanha family, Wailmer family, Corphish family, Feebas family, Staryu family, Psyduck family, Spheal family, Clamperl family, Relicanth, Corsola Chinchou family, Luvdisc, & Horsea family
Magma: Geodude family, Numel family, Slugma family, Sandshrew family, Trapinch family, Baltoy family, Vulpix family, Phanpy family, & Rhyhorn family
(While Magma looks small its just compared to Aqua, in addition they can increase it by throwing in other Pokemon like Rock- and Grass-types)
But Aqua only sticks with the Carvanha family and Magma the Numel family! Now Emerald did give Aqua the Wailmer family and Magma the the Baltoy family... but than in ORAS instead Aqua was given the Grimer family and Magma the Koffing family (and yes they do match the team's theme, Grimer being living liquid sludge and Koffing having flammable methane gas). But they're Poison-types, not the team's "special" type(s) (though if they wanted to add more type variety on their team they could have gone even further with paired Pokemon. Would make sense for Aqua to get Lunatone & Lileep family while Magma got Solrock & Anorith family)! We could have also had Archie and Maxie using a full team of 6 instead of 4. *sigh*