Yeah, agreed. Charizard is far better than arcanine, mostly because of its move pool, though you have to be careful because it takes a four times weakness against rock type attacks, however you take no damage from ground types... I'd guess it's worth it. Just have it hold a focus sash. Oh, and Samurott... Eh, you should switch him for a swampert, he's a bulky type(like Samurott), has access(as well as STAB) with the move earthquake which has a power of 100 as well as accuracy, hits multiple opponents in double/ triple battles and tends to bypass many types... I should shut up about that TM, huh? Anyway, swampert has no other weaknesses aside from the four times damage against grass moves, which are very common through the 'offline' game, however are never seen through online battles ^ ^ besides, charizard will be the most utter counter attack for grass types, glaringly due to its stab moves, speed, and of course his flying type(takes no damage from earhtquake), and finally because ground(swampert) moves are supereffective against rock types... Lol do you even like double battles?
P.s. Anyone could tell you're rather new to the game just by looking at your team, but I'll assume that because you've yet to beat the game, you have no access to either swampert or charizard. In which case I'll gladly trade you one(or both). Heck, I'm sure anyone could and would for no decent exchange, consider it a gift from PokemonWars!