To be fair though,
Venusaur in RGBY/FrLg was actually the best starter to get through the game with, as he had an advantage over five gyms and a neutrality to one.
On the other hand,
Sceptile is pretty bad against Steven, which is something it doesn't have in common with it's Hoenn counterpart starters.
As for competitive uses, Venusaur and Sceptile are both in the UU tier and are both very useful there as long as you stick to their strengths (Venusaur as an annoyer/tank and Sceptile as a sweeper.) It's also worth noting that Venusaur is alot more versitile than Sceptile due to the sheer number of roles he can play in a team (sweeper (albeit not a jaw dropping one,) tank, physical wall, special wall, annoyer, choice item user, etc.) Sceptile can really only do two things (sweep, subseed) although he does both very well
Meganium's got Sceptile beat when it comes to defensive and supporting moves and
Torterra is an excellent physical tank (only really fearing Ice Punch/Shard and Avalanche from the physical side of the spectrum.)
I don't think any of the Grass starters inherently "suck." Some (like Sceptile) are just more straightforward in their use (kick ass and take names) while others (Venusaur) require more patience and strategy in order to use them properly.
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