It really depends on what you are willing to spend. You will lose any ship you use to gank a Hulk in high-sec, and insurance rarely covers the cost of the gank! Even with a neutral ally there to loot and salvage the wrecks of your ship and your victim, you may bleed ISK quickly after a few goes.

It is possible to train a trial account in less than 2.5 days to pilot a 100 DPS Thrasher (minmatar destroyer) but you would probably need more than two of you to bring the DPS to the Hulk before you get concordokkened.

It is also possible to train a trial account to use a gank-fitted Hurricane in 7 days, spending 40+ million ISK to buy and fit it. (300 DPS with cheapest ACs, HAMs and medium drones.)

For both, you need the very minimum in skills for the ship itself, and the autocannons/missiles/drones, and then a few sundry skills like high speed maneuvering (for MWD), weapon upgrades, propulsion jamming and long range targetting (for a sensor booster - I hate it when they warp off before I get a lock!)

Gallente get the best ships for the job. Gallente Cruiser 4+, Medium Hybrid 4+, Weapon Upgrade I, and if at all possible Sentry Drone 4+ (not really worth training for unless you already have good drone skills).

Secret sauce: Thermodynamics I for that extra 15%

With sentries:

Vexor
4x Heavy Neutron Blaster I (or cheap named) with faction antimatter
4x Magnetic Field Stabilizer I (or cheap named)
scram, web, sensor booster with resolution script (lock them fast and pin them down)

3x Garde I (drones aren't effective because they waste their time flying around to the target and CONCORD will disable them when they do, sentries get 2-4 salvos in)

Without sentries:

Thorax
5x Heavy Neutron Blaster I (or cheap named) with faction antimatter
4x Magnetic Field Stabilizer I (or cheap named, can also do 5x)
1x Tracking Enhancer I (or cheap named, more likely to help then 5th stab)
scram, web, sensor booster with resolution script (lock them fast and pin them down)

5x Hammerhead I (they might get one hit, I wouldn't bother)

I group the guns, set the guns to F1, point to F2 and web to F3. Set keep at range to 500m.

1) Turn on scan booster. 2) Warp in at optimal (neutral scout FTW!) 3) Drop sentries (or drones) 4) Lock target and click keep at range (so I don't bump him, if possible). 5) F1 to F3, click the concord warning 6) Hit he drone "engage current target" hot key (I got mine set to Ctrl-Z).

Watch the fireworks.

You need 2 for most Hulks. 3x if well tanked.

For solo ganks, Brutix might work. Megathron with 5x Garde I is the Pro choice. Used to be dirt cheap using meta-3 mods (~4.5 million ISKs) with the old insurance scheme.