Tough one, I like Blastoise over Swampert, Sceptile over Venusaur and I can't really decide between Blaziken and Charizard. Looking at their first stage I'll have to go with the Hoenn starters, because I like them all and I never realy liked the designs of charmander and bulbasaur...
My actual vote for favourite starters goes to the Johto starters..
Venusaur vs. Sceptile
Sceptile's awesome, I won't lie. It and its pre-evolutions have some of the most epic Grass-type starter designs ever. However, in my honest opinion, Venusaur has better typing in Poison (especially with Fairy's introduction) and a better movepool by far. Aaanndd Bulbasaur is adorable.
Charizard vs. Blaziken
I think that this is really a toss-up. Whereas Charizard is one with the better design in my opinion, Blaziken's stats are more suited for its type. Charizard, being more Specially oriented, does not fit its secondary typing of Flying very well, as it does not have very powerful Special moves. With Blaziken's mixed attack stats and Fighting type (with much better moves may I add) I think Blaziken is a more powerful force (even though that's probably not a popular opinion). Even so, Torchic is so much worse than Charmander.
Winner: (By a very close margin) Blaziken
Blastoise vs. Swampert
All right, I'm gonna come out and say it, I love all of the Kanto starters, and Blastoise is no exception. It's bulky, it's a Water type, and it has decent attacking stats as well. Even so, I think that Water/Ground is a better typing, and Swampert is very well suited for it. Great attack, decent defenses, awesome move pool, I love it. Also, Mudkip, although Squirtle is KAWAII.
Venusaur vs. Sceptile
Venusaur would win over Sceptile in a fight, but i'm more receptive to the design of Sceptile and i like it's somewhat versatile movepool.
Swampert vs. Blastoise
I have really bad memories of Blastoise and very fond memories of Swampert. Going with Swampert once again on the basis of design and utility.
Charizard vs. Blaziken
Charizard. Typing advantage, i like the design better of Charizard, and he was my original starter so i'm biased.
Venusuar is great but Sceptile is just a fast and heavy hitter,something you need in pokemon,Venusaur is bulky and strong sure but Sceptile is just so much faster and could probably break Venusaur forever.
Blastoise Vs Swampert
Swamped,he wins not only because he has the highest stat total of all starters,but because he got me past something that even trumps Whitney in his level of nothing can stop me. Watson. If you picked any other starter you're in for a hell of a ride with this guy. Blastoise has good defense but swampert has a great movepool to counter.
Charizard vs- I don't have to tell you,Blazekin is like charizard only he's faster and not as frail as an old lady! Charizard is weak,if he wasn't fast people would crown bloody blastoise as the most overrated pokemon. But sadly Blaze did start the 3 gen long fire fighting starters....
It is a difficult choice between Lizardon and Bursyamo but for others I will definitely pick Hoenn starters over the Kanto ones. Jukain certainly beats Fushigibana since it is faster and plenty of Physical moves such as Leaf Blade. Moreover Mega Jukain also got one immunity and two double resistance which is better than Fushigibana which has none. Laglarge beats Kamex because it has got a secondary type which is immune to the greatest weakness Electric type in my opinion. Although it has double weakness against Grass types but it is easily dealt with Ice attacks.
Blastoise and Swampert
Blastoise has rapid spin and hydro cannon. However Swampert's typing makes it impervious to electric types, which was always a plus for me. Blastoise was always bulky, but Swampert takes the cake on this with its typing.
Sceptile and Venusaur
Sceptile was a boss. Sceptile still is a boss. I am going to be picking Treeko once I pick up Alpha Sapphire. However Venusaur learning Giga Drain, having bulk and overall having better typing Poison/Grass especially in this new generation where the fairy type has been introduced, downgrades Sceptile a lot. As of Generation V, Sceptile has yet to learn Leech Seed, Solar Beam or Petal Dance. Thats a shame and I understand he is awesome and TMs are reusable now so he can learn Solarbeam and breeding blah blah blah, however thats a little ridiculous. But after ripping on Sceptile for most of my analysis for these two Pokemon, its about a tie for both of them. Sceptile is really useful in a region with a lot of water. Also Sceptile can take on Roxanne, Wattson, and Wallace/Juan very easily. And if you are going up against Team Aqua then you are really getting it easy. Venusaur also is very useful in its region as well. Venusaur can storm through the first three gyms with the snap of a finger, depending on what game your playing Venusaur can also take on Giovanni very easily (Gen III). If your starter has learned poison moves yet, it can destroy Erika as well. The only gyms that really give Venusaur problems are Blaine's gym and Sabrina's gym, however they are so late in the game that if you played smart you would have types to cover your Venusaur.
So its a tie, both are very useful.
Blaziken and Charizard
Charizard is weak to Rock, Electricity and Water while Blaziken is weak to Flying, Rock, Ground, Water, and Psychic. Those are a lot of weaknesses for two very loved Pokemon. I love both Charizard and Blaziken. They both have served me well in past games. However, Charizard could fly throughout Kanto and its flamethrower took down most enemies. As fun as Blaziken was to use... Charizard was always a step ahead. Charizard has less weaknesses, can fly, and can take on most of the elite four. Hah, for two pokemon that were very disadvantaged in both of their regions its ironic how they come out the strongest. Depending on how you use them, both are amazing. This one goes to Charizard though because;
1. Charizard isn't taking on a region full of water trainers
2. Charizard has less weaknesses
3. Charizard was much much more useful to me at the end of the game. Blaziken had some trouble in the Elite 4.
Now if we are talking about fights here well here goes:
Charizard vs Blaziken: Anything could happen here because Charizard has flying moves but Blaziken has some rock moves. However I think Charizard would easily aerial ace him in one second and it would be over. I mean Charizard has higher base speed for a reason amirite?
Blastoise vs Swampert: This would be a weird battle. So I am going to call it a tie because honestly both of them can fight.
Venusaur vs Sceptile: Anyone saying Sceptile even has a chance. Is lying to themselves. Seriously. I shouldn't even have to explain why Sceptile would be dead here.
OK, putting aside my generic hatred of the extremely subpar gen 3 starters (mostly) for an analysis.
Blastoise vs Swampert
Tough one. Blastoise is better in all around defenses, but the ability to be immune to Electric moves is kinda awesome. I'm tied here, but in all honesty, I'm gonna have to say Blastoise. Defenses are good in ALL situations, immunity only helps against Electric. Plus, the quad Grass weakness isn't great...
Charizard vs Blaziken
Charizard wins hands-down here. Blaziken is cool and all, but Charizard is better, due to the inherent speed and power. Plus, Flying is a lot better ingame than Fighting, due the versatility since Physical/Special split. And the ground immunity.
Venusaur vs Sceptile
Venusaur's second type is better, plus Sceptile's only virtue is it's speed. Venusaur has bulk, and can actually use its movepool. Although, Poison doesn't exactly help it too much. The clincher is Sceptile's great physical moveset... and its subpar Attack stat.
Venusaur vs Sceptile
I love all the grass starters but Venusaur wins this one, even though I'd prefer MSceptile over MVenusaur but then I find Bulbasaur and Ivysaur over Treecko and Grovyle.
Charizard vs Blaziken
I don't need to think for a second before declaring Blaziken the winner. I can't stand Charizard and it's so overrated. Also Torchic is cuter than Charmander, though Charmelion is way cooler than Combusken. As for megas, neither of the MCharizards can hold a candle to MBlaziken
Swampert vs Blastoise
This is the closest one. I'd prefer Mudkip over Squirtke any day but Blastoise is slightly cooler than Swampert. Marshtomp and Wortortke are both quite adorable and I can't decide between them. MBlastoise is cooler than MSwampert so I'll give this to Blastoise
Overall though the Hoenn ones as a collective are better than the Kanto ones. That said I totally prefer Johto starters over everything else (my first game was Crystal).
Blaziken vs Charizard: Charizard KANTO
Torchic vs Charmander: Charmander KANTO
Swampert vs Blastoise: Blastoise KANTO
Mudkip vs Squirtle: Mudkip HOENN
Sceptile vs Venasaur: I can't decide This! ???
Treecko vs Bulbasaur: Bulbasaur KANTO
Sceptile easily beats out Venusaur for me, and is my favorite Grass Starter, although based on design I prefer Grovyle to his evolution. Venusaur is the only one of these six I've never played through a game with (although I have picked Bulbasaur for dex completion and am currently using a Bulbasaur in the fan made game Pokemon Zeta) and I'm not a huge fan of it, although it's undoubtedly more useful in battle than Sceptile.
Winner: Treecko, Grovyle, Sceptile
The second decision is incredibly difficult for me, as these are my two favorite starters of any gen, however Charmander was my first Pokemon ever discounting the TCG, and Mega-Charizard X is my second favorite Pokemon of all after Rayquaza.
Winner: Charmander, Charmeleon, Charizard
Finally I think I'd pick Swampert between the two. I've always liked Blastoise somewhat, but I've never loved him. Swampert was a distant third favorite after Blaziken and Sceptile back when I started Emerald, and I wasn't really a fan of him in general, however he's grown on me considerably over the years, enough to surpass Blastoise and take the spot as my third favorite Water starter after Empoleon and Feraligatr.
This. However if it came to a fight I wouldn't have trouble believing the Kanto starters could beat out Hoenn. When it comes to gameplay and learnsets I'm pretty sure Venusaur and Charizard have an edge.