What beats Suicune in Pokemon Go? The best choices are electric types. Despite being a pure Water type, Suicune has a fairly large pool of Ice type moves at its disposal including Ice Fang as a quick attack and Ice Beam as a charged attack.
Because of this, while Grass types might be able to pull off super effective moves against Suicune you may find yourself in a tricky spot if it starts coming out with some super effective damage of its own. Electric types are a little more reliable in this match up.
What Beats Suicune Pokemon Go: Best Choices
Raikou is going to be your best option. Being part of the same legendary trio as Suicune, Raikou is comparable stats wise but has the advantage type wise.
Zapdos can also go toe-to-toe with Suicune, but just be careful of those super effective Ice type moves. Magnezone is also a good choice. Being Steel and Electric type, it has resistance against Suicune's Ice and Psychic type moves and good options for super effective electric type moves.
Most Electric type Pokemon will do well in this match up, just be careful with Alolan Raichu, Suicune has the option to use Snarl as a quick move. Suicune can be found in Raids as well as won in battles with Giovanni.