Starters: which do you feel was most useful?

There are a lot of starter Pokémon in the main series now. From Bulbasaur to Sobble, the range is very wide and there should be at least a few everyone likes!

Which starter did you feel was most useful to you in a playthrough? This is mostly for going through a particular game/region using a starter selectable within it, but it can also be for starters that you used in games which don't have them available at the beginning (such as the Torchic Mystery Gift in XY, but its ability to Mega Evolve may not make it a fair comparison).

Which starter did you find the best to use in-game?

I found Mudkip sooo good in RSE. Great typing generally and a very good moveset to go through the games with. Can't really go wrong with Surf, Earthquake, and Ice Beam!

Easy. Probably...wait. Who was good? Definitely not Treecko, Snivy, or Sobble. Brought their type and nothing else. Doubts Totodile with its bad Special Attack stat. Remembers being irritated with Piplup fearing Ground moves on Rock-types. Spent too little time with Scorbunny and Popplio to say.

Leaves Squirtle, Froakie, and Litten. Given those, probably Froakie. Learns a wide range of physical and special moves as Greninja. Includes Night Slash, Dark Pulse, Extrasensory, Rock Slide, Grass Knot, Ice Beam, and Power-Up Punch. Uses both offenses competently (base 95 Attack and 103 Special Attack). Rounds this out with great speed (base 122) without sacrificing defense like Sharpedo does.

I find Swampert to be extremely good in Hoenn.

Yes, I was about to write the same thing. I found Mudkip really useful in Hoenn games. It has a really good advantage of typing against most of the gym leaders and has really good moves. It's also quite resistant imo.

I always choose the water type starter and I think I have never had the advantage I had in Hoenn with Mudkip!

Mudkip:
Swampert, in a region with not even one Grass type specialist to worry about, is broken. Learns EQ on its own, and like all Water starters in Gen 1-4 it has the advantage that Surf was HM so unlimited usage (and also helps navigating through Hoenn's large water sections). Empoleon is also kinda OP due to its typing, but it's somewhat balanced with its not so great offensive pool.

Bulbasaur:
Has probably the most favorable early game. All types Grass is good against have a gym in Kanto. Learns utility moves such as Leech Seed and Stun Spore to help catching other Pokémon. And its HP recovery moves are very useful in Kanto's caves and long routes, especially in first playthroughs. So, although Venusaur struggles defeating a lot of things, it is a very useful Pokémon in-game.

Chimchar:
Infernape has amazing offensive typing and move pool, that helps against a lot of things in Sinnoh. Gets two 120 BP physical STAB moves on level up, while still having enough Special attack to break through physical walls if necessary. Very versatile Pokémon that can learn a lot of coverage to counter almost everything in the game.

I'm aboard the Mudkip train as it was the first to come to mind after reading the question and before reading on lol

Primarina is also pretty good in Alola. Although Primarina being kind of slow prevents it from being amazing, the typing still helps a great deal throughout the Alola games.

To be honest most of them were pretty good, like, none of them sticks out as memorably not useful (except for Chikorita).

I guess any one of the Galar starters? You get access to so many good Pokemon early on that they lose their luster and feel more disposable than the other starters to me.

Swampert bodied Hoenn, large in part to the aforementioned lack of Grass type specialists, so it was a lock-in for me every time I played through that region. Runner up would be Torterra thanks to nostalgia bias; I ran through Sinnoh with it as my main (and only) team member the first time I played thru I think. I distinctly remember being in the Level 70's when I faced the Elite 4

Tepig is the first one that came on my mind. It can easily solo whole Unova in both BW and B2W2.

Mudkip is the beast in Hoenn. And it's also helpful that it can learn all necessary HMs.

Chimchar line is also great, but it's mostly because Infernape is overpowered.

As has been mentioned, early-game Bulbasaur is one of the most useful as it single-handedly gets you through the first two gyms before the game opens up and you get a more varied team. Mudkip - aside from the battle with May outside of Slateport where I found her Grovyle to be devastatingly effective - owns Hoenn. Can confirm whoever mentioned Tepig as I was so unenthused with all the non-Unova pokémon in B2W2 that I solo'd it until I could catch a Sandile (although a lone Archeops in Mistralton Cave nearly cleared out my team without taking damage using Aerobatics).

Chimchar is definitely one of the best ones, even though I usually use Piplup. Once you get Mach Punch you have super-effective coverage on gyms 1, 2, 6, 7, and E4 1. Plus Maylene's Lucario, and Flint's non-Fire-types.

Not technically a starter as you get given a standard one, but Libero Scorbunny might be the most OP starter ever. Facing a Ground-type? It gets Acrobatics by TM, so now you're immune! Rock-type? Fighting!

While I think every single starter Pokemon is useful no matter which one you pick...

If we're going simply by how useful they are in the games they're native to:

Bulbasaur makes the game the easiest because it can defeat the first two gym leaders with no problem, having an advantage, and doing neutral damage to Lt. Surge's Pokemon is still pretty good. Bulbasaur is effectively making the Kanto games easy mode, if you really think about it.

For Johto, I'd probably have to go with Cyndaquil Or Totodile, (sorry Chikorita, I love you, but you really make the game difficult), Totodile moreso in the early game because it has access to a dark type move and can defeat Ghastly with ease. But Cyndaquil is good for the early game in ways, too.

For Hoenn, while Treecko is my absolute favorite, Marshtomp (not Mudkip) is the most useful having only one weakness in Grass is really helpful in the long run of it all. It makes Wattson far more manageable.

For Sinnoh, I think all of them have their advantages. There's no clear winner. Chimchar can learn Mach Punch and counter Roark's rock types pretty well, Piplup has a pretty good moveset, and Turtwig is pretty good still late game. But, if I had to say which one shines above everyone else in terms of being slightly more useful, I'd have to go with Chimchar.

For Unova, all the starters are really disappointing in their final forms. The fact that only Emboar has two types is just unfairly balanced. Never really found any of them particularly "useful" but, I guess Razor Shell on Samurott is pretty good, Heat Crash on Emboar is very nice, and Coil on Serperior was alright. Beyond that, these were pretty underwhelming final forms.

I cannot say much for Kalos, I'll be honest: I benched my starter in these games. I really cannot speak for if they're useful or not because I simply did not enjoy Chesnaught or Delphox at all. Greninja is alright, though, I guess. To be honest, X/Y are so grossly easy that they're useful by default.

For Alola, this is a difficult thing for me to say. All of these starters have their own utility that makes them useful especially since they all got their own personal Z-moves. Since Alola is pretty different from any region before it, all of them are incredibly balanced Pokemon that can get you through the whole game.

For Galar, I again think they're all pretty useful considering the first three gyms are the starter types anyway. For the most part, since they all have their own signature moves. If you're not taking Hidden Abilities into account, I think they all have their own niche and you can run with them just fine.

But, the earlier generations clearly had one starter leaning towards being more useful than others, and it shows.

Hard question since all starters are made to be very similar when it comes to strength and usefulness level so it mostly comes down to personal experiences I guess. I've used every starter (except Sobble) in their respective region/generation at least once and the three that come to mind immediately are Venusaur, Feraligatr and Swampert.

I'll rank these three like this:

3. Venusaur. It's my favorite starter and it's amazing in Kanto. In Gen 1 it dominates with crits from Razor Leaf and in Gen 3 it's still the best starter choice even without broken crit mechanics since it matches up great against most Kanto Gyms. It's also amazing in Kalos with its new mega form and also it beats the newly added Fairy type. However it's only number three because it isn't as useful outside of battle as the Water types since it doesn't get many HMs outside of Cut and Cut isn't very good.

2. Swampert. Swampert is amazing both in battle and outside of it thanks to it learning HMs like Surf, Waterfall, Strength and Dive in a region where you really need all of those, especially the water ones, to fully enjoy what the region has to offer. Having only one weakness and access to imo best move in the game in Earthquake makes Swamper objectively the best starter choice in Hoenn. It's also amazing against the Champion and its ace Pokemon in every Hoenn game other than Emerald. In ORAS it even gets a mega that makes it even better.

1. Feraligatr. Very similar to Swampert since it's also a Water type that learns all the big water HMs you need to travers the region, very useful. Also super strong and matches up great against most big battles in Johto, especially since it gets Ice Fang very early. It's great for the last Gym and even against a lot of the Elite 4 thanks to it's good movepool. It's also the best Johto starter against Champion Lance and it makes that battle a lot easier thanks to the Ice Fang once again. As I said, it's very similar to Swampert when it comes to usefulness but I put it above Swampert because of my personal bias since I like it more than Swampert and I understand that most people would put Swampert at number 1 but for me personally Feraligatr is the most useful.

Most useful vs. which I liked more? That's harder than I would gave expected..

I gotta give props to Venusaur for being just for being a total ace.. but also Primarina for being so versatile..

And my bois Feraligatr and Decidueye were just *fun*, super useful in their respective games but also just enjoyable.

Man, I dunno if I can really give a good answer here. lol.

The water types seem to be mostly good as a whole! Swampert was obviously excellent, but Feraligatr was also very good with its diverse movepool. Always loved giving it Ice Fang/Ice Punch, Waterfall/Surf, and other moves depending on if I was playing the originals or remakes.

In Red/Blue I always found Blastoise to be very useful (or most useful when I was a kid). Water is a good type and it definitely helps that Ice Beam And Blizzard are very useful moves against Grass Types. I think nowadays I tend more towards Venusaur.

I can accept that Chikorita is the least useful in gen 2 but generally I don't really notice a huge difference in that generation in regards to the starters.

Gen 3 is kinda similar for me. Swampert's Ground typing helps it out a lot, though. I've only had three major playthroughs in Hoenn games and actually ended up using all three starters, as well. So, I'm not too heavily swaying towards one in particular.

Gen 4 is Infernape simply by virtue of being a Fire Type in a region that severely lacks Fire Types.

Gen 5: no real preference, tbh.

Gen 6: Greninja, probably. Water types are good.

Gen 7: I've only ever used Rowlet so I don't know how well the other two do. I would guess they are about equal, though.

Gen 8: no clue, tbh. I used Scorbunny in my first play through but it didn't feel anything special. I picked Sobble in my second playthrough but quickly replaced it with something else...I'd guess the three are very similarly useful?

Bulbasaur in generation 1, the 2 first gyms are easy. :)