Krillin can help. But Tien will beat Frieza in all rounds. Atleast Tien is SSJ2 level
His tri-beam may be at SSJ2 level but his strength aren't at that level. Tr-beam expands the energy output, leaving the user as almost dead tired (Tien vs Semi P Cell) and moreover he got him off guard. Frieza is fast enough to avoid the tri-beam attack, if it hits him than its a different thing.