4Game

I did this for fun but this gets really long so sorry if the descriptions are super basic or generic, but writing a full length answer for everything would be very tiring.

AA: Ice/ghost. Ice elemental with a ghostly apparition as it's appearance.

Abaddon: Ghost/dark. Mists and vapor best fit with ghost and dark types.

Alchemist: Poison/Fighting. Poison for alchemy, fighting for a beefy ogre trained in fighting.

AM: Dark. This might be a weird one, but if he is the ANTI mage, and most mages are psychic, I think it makes sense that he is immune to them and deals super effective damage. Also his ways might be a bit twisted.

Arc Warden: Electric. Has a lot of undertones of magnetism and electric pulses in his kit.

Axe: Fighting. Generic brawler.

Bane: Dark. An elemental based off of fear.

Batrider: Fire/Flying. Flies on a bat and has many fire related spells.

Beastmaster: Ground. Controls creatures, which generally suggests a command over nature, so ground fits best.

Bloodseeker: Dark/Fighting. Hardest one to place for me but his methods of fighting are twisted.

Bounty: Normal. Kinda just an average cat-like creature that can sneak well.

Brewmaster: Normal. Until he ults, he is just a panda that drinks a lot. Afterwards he becomes fire/flying/rock/dark based off of the pandas, but overall I think he stays normal

Bristle: Fighting. Just a brawler.

Brood: Bug. Just a giant insect

Centaur: Normal. Fighting could be argued but generally if the creature is just that animal, in this case just a centaur, they are normal type.

Ck: dark. Best fit for chaos.

Chen: Normal. Just a guy pretty much, and his methods of mind control don't really make me think of psychic.

Clinkz: Fire/Ghost. Burning skeleton.

Clockwerk: Normal/steel. I gave many (but not all) keens the normal type since many of them are just a person in a suit.

Cm: ice. Controls ice magic.

Dark seer: Psychic. Even though he has dark in his name, he doesn't have twisted methods. Is a commander and has control over some unknown magic.

Dark Willow: Dark/Fairy. Twisted and Sadistic fae creature.

Dawnbreaker: Fighting. Nothing fits dawn super well so fighting seemed like the best fit.

Dazzle: Poison/Dark. Has weird, twisted magic.

Death Prophet: Ghost. Is pretty much just a ghost that cant die.

Disruptor: Electric. Electric mage.

Doom: fire/ground. Considering doom is essentially lucifer from Christian mythos, the ground type (rules over the earth) makes sense to me, and scorched earth can easily have a "ground" component to it.

Dk: steel/dragon. Armored knight that turns into a dragon

Drow: ice/fighting. Has some kind of ice magic and is a skilled archer.

Earth Spirit: ground/rock. Has command over the earth itself, in both the land and in rocks.

Earthshaker: ground. Earth incarnate.

Elder titan: ground. Created the world, and many of his spells effect the ground.

Ember spirit: fire. Fire incarnate.

Ench: grass/fairy. Fae-like creature with healing and nature magic.

Enigma: dark. Void elemental.

Faceless void: dark/psychic. Has some kind of future prophesizing, and control over time.

Grimstroke: dark/ghost. Is a very twister character and has control over spirits.

Gyro: normal/flying. Flies a machine.

Hoodwink: grass. uses many plant-based spells, like acorns and a wood-looking dart for her ult.

Huskar: fire. uses fire magic of some sort, and most other types don't fit (IMO)

Invoker: psychic. very intelligent. I don't think dark fits super well.

Io: electric. Magnetism and atoms.

Jakrio: ice/fire. Even though he's a dragon, I think that would have to come from an ability. Ice/fire is a core concept of jakiro.

Jugg: fighting. generic swordsman

Kotl: normal/psychic. Many light based spells are normal type. Psychic type is debatable.

Kunkka: water ghost. Ghostly pirate with command over the tides.

Legion: steel/fighting. Heavily armored warrior.

Lesh: electric/dark. Many of his spells have to deal with electric energy, and he has a very twisted mind.

Lich: ice/ghost. Ghostly ice mage.

Lifestealer: dark/fighting. Twisted beast.

Lina: fire. fire mage

Lion: fire. fire mage pt 2

Ld: ground. Nature magic (druid).

Luna: dark/fairy. Debatable on fairy but most moon based attacks are fairy type so I gave it to her and mirana. Luna is more cruel than mirana

Lycan: ground. Not a whole lot fits lycan tbh. Dark is sort of hit or miss, normal is too basic. Ground sort of fits since he is a beast of the earth that can summon wolves at command.

Magnus: electric. kinda similar to lycan, not a whole lot fits magnus. Electric fits though since he has control over magnetic poles.

Marci: normal/fighting. regular girl with super strength

Mars: steel fighting. skilled fighter with a huge shield.

Medusa: ground. Snakes are typically creatures of the earth, and she is turned into one and can launch other snakes as people.

Meepo: ground. Creature that lives underground

Mirana: normal fairy. same reason as luna. normal since mirana is less cruel and more "average" in terms of fighting prowess.

Mk: fighting. legendary warrior.

Morph: water. literally water.

Naga: water. creature of the sea.

Np: grass. Nature magic that better fits in grass than ground.

Necro: poison/ghost. Plague mage that is sort of undead.

Night stalker: dark flying. Terrifying creature that can fly

Nyx: bug psychic. a bug that can hurt the mind (mana burn)

Ogre: normal/fire. a regular ogre with light fire magic, blessed by the goddess of luck. I think normal fits the "luck" category the most.

Omni: steel. Weird one but is pretty well armored so I guess steel.

Oracle: dark psychic. prophet that forsees the future

Od: dark psychic. otherworldly being.

Pango: ground. Creature of the earth, with many land-based spells.

Pa: fighting. skilled assassin

Pl: fighting. not a whole lot fits pl but giving him normal doesn't feel right either, so fighting it is.

Phoenix: fire flying. a phoenix… yeah that's it lol

Primal: dark. unhinged beast.

Puck: fairy dragon. fae dragon

Pudge: poison. closest to anything pudge will fit into, with stenches and dismembering.

Pugna: ghost. undead mage, the magic seems to be of a different realm so its hard to give him anything else I think. ghostly magic is honestly the best descriptor imo.

Qop: poison dark. succubus with poisonous daggers.

Razor: electric/dark. whips people to their destination in the after life with an electric whip.

Riki: normal. kinda just a dude. Not particularly skilled at fighting from what I can tell, just very stealthy.

Rubick: psychic. powerful mage.

Sand king: bug ground. scorpion form of the being of sand.

Sd: poison dark. cruel cult master that has poison spells.

Sf: dark. demon lord.

Shaman: psychic. not a whole lot fits shaman either but he has some sort of magic so psychic kind of fits.

Silencer: psychic. intelligent mage.

Sky: psychic flying. skywrath people are mages that live in the clouds.

Slardar: water/fighting. Slitherine body guard

Slark: water dark. sadistic fish creature

Snap: normal fire. normal for snap, fire for her mount.

Sniper: normal. nothing fits sniper. Normal fits better than steel for just bullets, imo

Spec: ghost. spectral being.

Sb: dark. planeshifter.

Storm: electric. air/storm elemental.

Sven: fighting. skilled fighter.

Techies: steel fire. this is the best I could come up with for bombs.

Ta: psychic fighting. skilled assassin with psychic powers to protect herself.

Tb: dark. sadistic demon.

Tide: water. leviathan

Timber: steel normal. normal guy in a tree killing mech

Tinker: psychic. very intelligent keen and nothing else fits him really.

Tiny: rock. stone golem

Treant: grass ground. treant with lots of nature magic.

Troll: fighting. debatably could be dark but he's more angry than sadistic I think?

Tusk: ice fighting. Brawler from the north

Underlord: dark fire. Powerful demon that can summon hellfire.

Undying: ghost. Zombie is close enough to ghost and not much else suits him

Ursa: normal fighting. a bear that is very skilled at fighting

Venge: dark. sadistic ex-skywrath

Veno: poison. venomous creature

Viper: poison flying. venomous creature pt 2

Visage: ghost flying. looks pretty ghostly and can turn invisible, and holds power over the underscape.

Void spirit: dark psychic. void elemental.

Warlock: dark fire. sort-of cruel master of summoning, calling forth a fiery demon.

Weaver: bug. even though he has a lot of time powers, that isn't really a type and I'm not going to give weaver dragon. so pure bug it is.

Wind: normal. Flying didn't feel right, so probably just normal with a lot of flying type moves.

Wyvern: ice dragon. wyvern that has ice breath and powers.

Wd: poison. lots of unusual magic and potions.

Wk: ghost. undead being, debatably a ghost.

Zeus: electric. powerful wielder of magic.

Sorry if those were very basic descriptions but there is a LOT of dota heroes. So in total,

Dark: 27

Fighting: 20

Fire: 14

Grass: 4

Water: 6

Electric: 8

Psychic: 14

Ghost: 13

Normal: 16

Ice: 7

Ground: 12

Rock: 2

Bug: 4

Poison: 9

Flying: 7

Steel: 7

Dragon: 3

Fairy: 5

Fairy types are the strongest against the majority of heroes, being super effective against dark and fighting types. So start spamming puck, mirana, luna, dark willow, and ench!