Alchemist? Bring blue potion and heal the SP. And you can use white potions for 4-5k heals on tanks. Potion pitcher is cool, you know? - aid pot is very good, and useful, however, a) white potting is abit of a waste unless its an emergency, when theres priests to heal for free, and who's guna choose a alchem over a scholar? no one. So yeah, alchem might have some uses, but there are better options, which party leaders will of course take, and the in the unlikely event that you did get chosen to do the job you would probably have to be a billionaire to afford the amount of blue pots that would be needed, best just keep the zeny and buy blanks/a leech.
As a player who loves alchies, I find it amusing that someone would think alchies are anywhere nerfed or useless. It's true that we don't have superawesome AoE skills, but we have our own nice points:
Before we start, let's point out the obvious: whoever doesn't want to spend zeny is several times less useful and several times slower than the same character spending zeny. So... we won't count zeny as a limit. It's not like you see priests neglecting safety walls because it costs gems, whitesmiths neglecting maximum overthrust and HSCR because it costs zeny, scholars neglecting fiberlock because webs cost zeny, snipers neglecting cursed waters because it costs zeny, any character carrying an emergency flywing, some potions, an ygg leaf because it costs zeny, and so on. If someone wants to be a gimped chara because they are greedy, it's their own fault.
Alchy is the only class that can easily afk level to 99, and it doesn't take a lot of time. Alchy is the only class that can have a free battlemanual at all times (homu + merc tapping, somewhere like anubii works wonders always for me). Alchy has a decent spammable high damage skill that costs laughable SP, can recover SP and HP fast, can have free speedpot movement, can carry over 12 thousand weight without spending a single stat point in str... can heal a lot faster than a priest and for far more... plus it has the increased recovery of increase-hp-recovery + increase-sp-recovery in one skill, that also increases its potting success, and also increases how much does he/her heals...
...and when you trans, you can turn into a killing machine that still has a super-nice potting success without compromising your build(unlike a blacksmith for example), and now you don't only heal more and faster than a priest, but also do so in an AoE... reallistically being able to solo or duo dragons while pulling all your alts or friends with you. Alchy is neither a weak or hard class to level at all.