Razor Leaf + Ice Beam and Hydro Pump

Razor Leaf takes advantage of STAB to deal large amounts of damage without worrying about being shielded. Unfortunately it also has the worst energy generation in the game.

Ice Beam offers good coverage, and is almost mandatory due to its energy cost being significantly cheaper than the rest of Ludicolo's charge moves. Hydro Pump, Blizzard, and Solar Beam all demand incredible amounts of energy for their usage, which may be unrealistic due to Ludicolo's lack of significant energy gains. Any of these options could be viable (though Blizzard is somewhat redundant due to Ice Beam), but don't expect to use them often, if at all.

Bubble + Ice Beam and Energy Ball

Some matchups might be favorable with Bubble, not only from a typing perspective, but also partly due to greater energy gains which are necessary for Ludicolo's costly charge moves. The addition of Energy Ball from the April 2020 rebalance improves Ludicolo's overall viability due to its other charge moves being incredibly costly (energy-wise).