Kalos had the least amount of Ice types, with 4.
If you're not counting Mega Pokemon, Kanto and Johto wins with 5.
Kanto (Generation 1) - 5 (Dewgong, Cloyster, Jynx, Lapras, Articuno)
Johto (Generation 2) - 5 (Sneasel, Swinub, Piloswine, Delibird, Smoochum)
Hoenn (Generation 3) - 6 (Snorunt, Glalie, Spheal, Sealeo, Walrein, Regice)
Sinnoh^^ (Generation 4) - 6 (Snover, Abomasnow, Weavile, Glaceon, Mamoswine, Froslass)
Unova (Generation 5) - 7 (Vanillite, Vanillish, Vanilluxe, Cubchoo, Beartic, Cryogonal, Kyruem)
Kalos^ (Generation 6) - 4 (Amaura, Aurorus, Bergmite, Avalugg)
^If you count Mega Glalie and Mega Abomasnow, this number would be 6.
^^If you count Rotom-F's type chance to Electric-Ice , this number would be 7.